# # For a description of the syntax of this configuration file, # see extra/config/Kconfig-language.txt # mainmenu "uClibc C Library Configuration" config DESIRED_TARGET_ARCH string option env="ARCH" choice prompt "Target Architecture" default TARGET_alpha if DESIRED_TARGET_ARCH = "alpha" default TARGET_arm if DESIRED_TARGET_ARCH = "arm" default TARGET_avr32 if DESIRED_TARGET_ARCH = "avr32" default TARGET_bfin if DESIRED_TARGET_ARCH = "bfin" default TARGET_cris if DESIRED_TARGET_ARCH = "cris" default TARGET_e1 if DESIRED_TARGET_ARCH = "e1" default TARGET_frv if DESIRED_TARGET_ARCH = "frv" default TARGET_h8300 if DESIRED_TARGET_ARCH = "h8300" default TARGET_hppa if DESIRED_TARGET_ARCH = "hppa" default TARGET_i386 if DESIRED_TARGET_ARCH = "i386" default TARGET_i960 if DESIRED_TARGET_ARCH = "i960" default TARGET_ia64 if DESIRED_TARGET_ARCH = "ia64" default TARGET_m68k if DESIRED_TARGET_ARCH = "m68k" default TARGET_microblaze if DESIRED_TARGET_ARCH = "microblaze" default TARGET_mips if DESIRED_TARGET_ARCH = "mips" default TARGET_nios if DESIRED_TARGET_ARCH = "nios" default TARGET_nios2 if DESIRED_TARGET_ARCH = "nios2" default TARGET_powerpc if DESIRED_TARGET_ARCH = "powerpc" default TARGET_sh if DESIRED_TARGET_ARCH = "sh" default TARGET_sh64 if DESIRED_TARGET_ARCH = "sh64" default TARGET_sparc if DESIRED_TARGET_ARCH = "sparc" default TARGET_v850 if DESIRED_TARGET_ARCH = "v850" default TARGET_vax if DESIRED_TARGET_ARCH = "vax" default TARGET_x86_64 if DESIRED_TARGET_ARCH = "x86_64" default TARGET_xtensa if DESIRED_TARGET_ARCH = "xtensa" help The architecture of your target. config TARGET_alpha bool "alpha" config TARGET_arm bool "arm" config TARGET_avr32 bool "avr32" config TARGET_bfin bool "bfin" config TARGET_c6x bool "c6x" config TARGET_cris bool "cris" config TARGET_e1 bool "e1 (BROKEN)" config TARGET_frv bool "frv (BROKEN)" config TARGET_h8300 bool "h8300 (BROKEN)" config TARGET_hppa bool "hppa" config TARGET_i386 bool "i386" config TARGET_i960 bool "i960 (BROKEN)" config TARGET_ia64 bool "ia64" config TARGET_m68k bool "m68k" config TARGET_microblaze bool "microblaze" config TARGET_mips bool "mips" config TARGET_nios bool "nios" config TARGET_nios2 bool "nios2" config TARGET_powerpc bool "powerpc" config TARGET_sh bool "superh" config TARGET_sh64 bool "sh64" config TARGET_sparc bool "sparc" config TARGET_v850 bool "v850 (BROKEN)" config TARGET_vax bool "vax" config TARGET_x86_64 bool "x86_64" config TARGET_xtensa bool "xtensa" endchoice menu "Target Architecture Features and Options" if TARGET_alpha source "extra/Configs/Config.alpha" endif if TARGET_arm source "extra/Configs/Config.arm" endif if TARGET_avr32 source "extra/Configs/Config.avr32" endif if TARGET_bfin source "extra/Configs/Config.bfin" endif if TARGET_cris source "extra/Configs/Config.cris" endif if TARGET_e1 source "extra/Configs/Config.e1" endif if TARGET_frv source "extra/Configs/Config.frv" endif if TARGET_h8300 source "extra/Configs/Config.h8300" endif if TARGET_hppa source "extra/Configs/Config.hppa" endif if TARGET_i386 source "extra/Configs/Config.i386" endif if TARGET_i960 source "extra/Configs/Config.i960" endif if TARGET_ia64 source "extra/Configs/Config.ia64" endif if TARGET_m68k source "extra/Configs/Config.m68k" endif if TARGET_nios source "extra/Configs/Config.nios" endif if TARGET_nios2 source "extra/Configs/Config.nios2" endif if TARGET_microblaze source "extra/Configs/Config.microblaze" endif if TARGET_mips source "extra/Configs/Config.mips" endif if TARGET_powerpc source "extra/Configs/Config.powerpc" endif if TARGET_sh source "extra/Configs/Config.sh" endif if TARGET_sh64 source "extra/Configs/Config.sh64" endif if TARGET_sparc source "extra/Configs/Config.sparc" endif if TARGET_v850 source "extra/Configs/Config.v850" endif if TARGET_vax source "extra/Configs/Config.vax" endif if TARGET_x86_64 source "extra/Configs/Config.x86_64" endif if TARGET_xtensa source "extra/Configs/Config.xtensa" endif if TARGET_c6x source "extra/Configs/Config.c6x" endif config TARGET_SUBARCH string default "e500" if CONFIG_E500 default "classic" if CONFIG_CLASSIC default "sh4" if CONFIG_SH4 default "" if CONFIG_GENERIC_386 || CONFIG_386 default "i486" if CONFIG_486 default "i586" if CONFIG_586 || CONFIG_586MMX default "i686" if TARGET_ARCH = "i386" default "" source "extra/Configs/Config.in.arch" endmenu menu "General Library Settings" config HAVE_NO_PIC bool config DOPIC bool "Generate only Position Independent Code (PIC)" default y depends on !HAVE_NO_PIC help If you wish to build all of uClibc as PIC objects, then answer Y here. If you are unsure, then you should answer N. config ARCH_HAS_NO_SHARED bool config ARCH_HAS_NO_LDSO bool select ARCH_HAS_NO_SHARED config HAVE_SHARED bool "Enable shared libraries" depends on !ARCH_HAS_NO_SHARED default y help If you wish to build uClibc with support for shared libraries then answer Y here. If you only want to build uClibc as a static library, then answer N. config FORCE_SHAREABLE_TEXT_SEGMENTS bool "Only load shared libraries which can share their text segment" depends on HAVE_SHARED select DOPIC help If you answer Y here, the uClibc native shared library loader will only load shared libraries, which do not need to modify any non-writable segments. These libraries haven't set the DT_TEXTREL tag in the dynamic section (==> objdump). All your libraries must be compiled with -fPIC or -fpic, and all assembler function must be written as position independent code (PIC). Enabling this option will make uClibc's shared library loader a little bit smaller and guarantee that no memory will be wasted by badly coded shared libraries. config LDSO_LDD_SUPPORT bool "Native 'ldd' support" depends on HAVE_SHARED default y help Enable all the code needed to support traditional ldd, which executes the shared library loader to resolve all dependencies and then provide a list of shared libraries that are required for an application to function. Disabling this option will make uClibc's shared library loader a little bit smaller. Most people will answer Y. config LDSO_CACHE_SUPPORT bool "Enable library loader cache (ld.so.conf)" depends on HAVE_SHARED default y help Enable this to make use of /etc/ld.so.conf, the shared library loader cache configuration file to support for non-standard library paths. After updating this file, it is necessary to run 'ldconfig' to update the /etc/ld.so.cache shared library loader cache file. config LDSO_PRELOAD_ENV_SUPPORT bool "Enable library loader LD_PRELOAD environment" depends on HAVE_SHARED default y help Enable this to make use of LD_PRELOAD environment variable. A whitespace-separated list of additional, user-specified, ELF shared libraries to be loaded before all others. This can be used to selectively override functions in other shared libraries. For set-user-ID/set-group-ID ELF binaries, only libraries in the standard search directories that are also set-user-ID will be loaded. config LDSO_PRELOAD_FILE_SUPPORT bool "Enable library loader preload file (ld.so.preload)" depends on HAVE_SHARED help Enable this to make use of /etc/ld.so.preload. This file contains a whitespace separated list of shared libraries to be loaded before the program. config LDSO_BASE_FILENAME string "Shared library loader naming prefix" depends on HAVE_SHARED && (LDSO_CACHE_SUPPORT || LDSO_PRELOAD_FILE_SUPPORT) default "ld.so" help If you wish to support both uClibc and glibc on the same system, it is necessary to set this to something other than "ld.so" to avoid conflicts with glibc, which also uses "ld.so". This prevents both libraries from using the same /etc/ld.so.* files. If you wish to support both uClibc and glibc on the same system then you should set this to "ld-uClibc.so". Most people will leave this set to the default of "ld.so". WARNING: Changing the default prefix could cause problems with binutils' ld ! config LDSO_STANDALONE_SUPPORT bool "Dynamic linker stand-alone mode support" depends on HAVE_SHARED help The dynamic linker can be run either indirectly through running some dynamically linked program or library (in which case no command line options to the dynamic linker can be passed and, in the ELF case, the dynamic linker which is stored in the .interp section of the program is executed) or directly by running: /lib/ld-uClibc.so.* [OPTIONS] [PROGRAM [ARGUMENTS]] Stand-alone execution is a prerequisite for adding prelink capabilities to uClibc dynamic linker, as well useful for testing an updated version of the dynamic linker without breaking the system. config LDSO_PRELINK_SUPPORT bool "Dynamic linker prelink support" depends on HAVE_SHARED select LDSO_STANDALONE_SUPPORT help The dynamic linker can be used in stand-alone mode by the prelink tool for prelinking ELF shared libraries and binaries to speed up startup time. It also is able to load and handle prelinked libraries and binaries at runtime. config UCLIBC_STATIC_LDCONFIG bool "Link ldconfig statically" depends on HAVE_SHARED default y help Enable this option to statically link the ldconfig binary. Making ldconfig static can be beneficial if you have a library problem and need to use ldconfig to recover. Sometimes it is preferable to instead keep the size of the system down, in which case you should disable this option. config LDSO_RUNPATH bool "Enable ELF RUNPATH tag support" depends on HAVE_SHARED default y if LDSO_CACHE_SUPPORT help ELF's may have dynamic RPATH/RUNPATH tags. These tags list paths which extend the library search paths. They are really only useful if a package installs libraries in non standard locations and ld.so.conf support is disabled. Usage of RUNPATH tags is not too common, so disabling this feature should be safe for most people. config LDSO_SEARCH_INTERP_PATH bool "Add ldso path to lib search path" depends on HAVE_SHARED default y help The ldso is told where it is being executed from and can use that path to find related core libraries. This is useful by default, but can be annoying in a mixed development environment. i.e. if the ldso is run from /foo/boo/ldso.so, it will start its library search with /foo/boo/ If unsure, simply say Y here. config LDSO_LD_LIBRARY_PATH bool "Add LD_LIBRARY_PATH to lib search path" depends on HAVE_SHARED default y help On hardened system it could be useful to disable the use of LD_LIBRARY_PATH environment variable (a colon-separated list of directories in which to search for ELF libraries at execution-time). If unsure, simply say Y here. config LDSO_NO_CLEANUP bool "Disable automatic unloading of dynamically loaded shared objects" depends on HAVE_SHARED default n help If you need complete allocation traces when debugging memory leaks using Valgrind in a process that dynamically loads shared objects, then answer Y here. Unlike glibc, uClibc unloads all dynamically loaded shared objects when a process exits, which prevents Valgrind from correctly resolving the symbols from the unloaded shared objects. Unless you know you need this, you should answer N. config UCLIBC_CTOR_DTOR bool "Support global constructors and destructors" default y help If you wish to build uClibc with support for global constructor (ctor) and global destructor (dtor) support, then answer Y here. When ctor/dtor support is enabled, binaries linked with uClibc must also be linked with crtbegin.o and crtend.o which are provided by gcc (the "*startfile:" and "*endfile:" settings in your gcc specs file may need to be adjusted to include these files). This support will also add a small amount of additional size to each binary compiled vs uClibc. If you will be using uClibc with C++, or if you need the gcc __attribute__((constructor)) and __attribute__((destructor)) to work, then you definitely want to answer Y here. If you don't need ctors or dtors and want your binaries to be as small as possible, then answer N. config LDSO_GNU_HASH_SUPPORT bool "Enable GNU hash style support" depends on HAVE_SHARED help Newest binutils support a new hash style named GNU-hash. The dynamic linker will use the new GNU-hash section (.gnu.hash) for symbol lookup if present into the ELF binaries, otherwise it will use the old SysV hash style (.hash). This ensures that it is completely backward compatible. Further, being the hash table implementation self-contained into each executable and shared libraries, objects with mixed hash style can peacefully coexist in the same process. If you want to use this new feature, answer Y choice prompt "Thread support" #default UCLIBC_HAS_THREADS_NATIVE if (TARGET_alpha || TARGET_arm || TARGET_i386 || TARGET_mips || TARGET_powerpc || TARGET_sh || TARGET_sh64) default HAS_NO_THREADS help If you want to compile uClibc with pthread support, then answer Y. This will increase the size of uClibc by adding a bunch of locking to critical data structures, and adding extra code to ensure that functions are properly reentrant. config HAS_NO_THREADS bool "none" help Disable thread support. config LINUXTHREADS_OLD bool "older (stable) version of linuxthreads" # linuxthreads and linuxthreads.old need nanosleep() select UCLIBC_HAS_REALTIME help There are two versions of linuxthreads. The older (stable) version has been in uClibc for quite a long time but hasn't seen too many updates other than bugfixes. config LINUXTHREADS_NEW bool "slightly newer version of linuxthreads" help The new version has not been tested much, and lacks ports for arches which glibc does not support (like bfin/frv/etc...), but is based on the latest code from glibc, so it may be the only choice for the newer ports (like alpha/amd64/64bit arches and hppa). config UCLIBC_HAS_THREADS_NATIVE bool "Native POSIX Threading (NPTL)" select UCLIBC_HAS_TLS select UCLIBC_HAS_STDIO_FUTEXES # i386 has no lowlevellock support (yet) as opposed to i486 onward depends on !CONFIG_386 help If you want to compile uClibc with NPTL support, then answer Y. IMPORTANT NOTE! NPTL requires a Linux 2.6 kernel, binutils at least version 2.16 and GCC with at least version 4.1.0. NPTL will not work with older versions of any above sources. If you ignore any of these guidelines, you do so at your own risk. Do not ask for help on any of the development mailing lists. !!!! WARNING !!!! BIG FAT WARNING !!!! REALLY BIG FAT WARNING !!!! This is experimental code and at times it may not even build and even if it does it might decide to do random damage. This code is potentially hazardous to your health and sanity. It will remain that way until further notice at which point this notice will disappear. Thank you for your support and for not smoking. endchoice config UCLIBC_HAS_THREADS def_bool y if !HAS_NO_THREADS config UCLIBC_HAS_TLS bool "Thread-Local Storage" depends on UCLIBC_HAS_THREADS_NATIVE help If you want to enable TLS support then answer Y. This is fast an efficient way to store per-thread local data which is not on stack. It needs __thread support enabled in gcc. config PTHREADS_DEBUG_SUPPORT bool "Build pthreads debugging support" depends on UCLIBC_HAS_THREADS help Say Y here if you wish to be able to debug applications that use uClibc's pthreads library. By enabling this option, a library named libthread_db will be built. This library will be dlopen()'d by gdb and will allow gdb to debug the threads in your application. IMPORTANT NOTE! Because gdb must dlopen() the libthread_db library, you must compile gdb with uClibc in order for pthread debugging to work properly. If you are doing development and want to debug applications using uClibc's pthread library, answer Y. Otherwise, answer N. config UCLIBC_HAS_SYSLOG bool "Syslog support" default y depends on UCLIBC_HAS_NETWORK_SUPPORT select UCLIBC_HAS_SOCKET help Support sending messages to the system logger. This requires socket-support. config UCLIBC_HAS_LFS bool "Large File Support" default y help If you wish to build uClibc with support for accessing large files (i.e. files greater then 2 GiB) then answer Y. Do not enable this if you are using an older Linux kernel (2.0.x) that lacks large file support. Enabling this option will increase the size of uClibc. choice prompt "Malloc Implementation" default MALLOC if ! ARCH_USE_MMU default MALLOC_STANDARD if ARCH_USE_MMU config MALLOC bool "malloc" help "malloc" use mmap for all allocations and so works very well on MMU-less systems that do not support the brk() system call. It is pretty smart about reusing already allocated memory, and minimizing memory wastage. This is the default for uClinux MMU-less systems. config MALLOC_SIMPLE bool "malloc-simple" help "malloc-simple" is trivially simple and slow as molasses. It was written from scratch for uClibc, and is the simplest possible (and therefore smallest) malloc implementation. This uses only the mmap() system call to allocate and free memory, and does not use the brk() system call at all, making it a fine choice for MMU-less systems with very limited memory. It's 100% standards compliant, thread safe, very small, and releases freed memory back to the OS immediately rather than keeping it in the process's heap for reallocation. It is also VERY SLOW. config MALLOC_STANDARD bool "malloc-standard" depends on ARCH_USE_MMU help "malloc-standard" is derived from the public domain dlmalloc implementation by Doug Lea. It is quite fast, and is pretty smart about reusing already allocated memory, and minimizing memory wastage. This uses brk() for small allocations, while using mmap() for larger allocations. This is the default malloc implementation for uClibc. If unsure, answer "malloc-standard". endchoice config MALLOC_GLIBC_COMPAT bool "Malloc returns live pointer for malloc(0)" help The behavior of malloc(0) is listed as implementation-defined by SuSv3. Glibc returns a valid pointer to something, while uClibc normally returns NULL. I personally feel glibc's behavior is not particularly safe, and allows buggy applications to hide very serious problems. When this option is enabled, uClibc will act just like glibc, and return a live pointer when someone calls malloc(0). This pointer provides a malloc'ed area with a size of 1 byte. This feature is mostly useful when dealing with applications using autoconf's broken AC_FUNC_MALLOC macro (which redefines malloc as rpl_malloc if it does not detect glibc style returning-a-valid-pointer-for-malloc(0) behavior). Most people can safely answer N. config UCLIBC_DYNAMIC_ATEXIT bool "Dynamic atexit() Support" default y help When this option is enabled, uClibc will support an infinite number, of atexit() and on_exit() functions, limited only by your available memory. This can be important when uClibc is used with C++, since global destructors are implemented via atexit(), and it is quite possible to exceed the default number when this option is disabled. Enabling this option adds a few bytes, and more significantly makes atexit and on_exit depend on malloc, which can be bad when compiling static executables. Unless you use uClibc with C++, you should probably answer N. config COMPAT_ATEXIT bool "Old (visible) atexit Support" help Enable this option if you want to update from 0.9.28 to git/0.9.29, else you will be missing atexit() until you rebuild all apps. config UCLIBC_SUSV3_LEGACY bool "Enable SuSv3 LEGACY functions" #vfork, # h_errno # gethostbyaddr # gethostbyname help Enable this option if you want to have SuSv3 LEGACY functions in the library, else they are replaced by SuSv3 proposed macros. Currently applies to: bcmp, bcopy, bzero, index, rindex, ftime, bsd_signal, (ecvt), (fcvt), gcvt, (getcontext), (getwd), (makecontext), mktemp, (pthread_attr_getstackaddr), (pthread_attr_setstackaddr), scalb, (setcontext), (swapcontext), ualarm, usleep, wcswcs. WARNING! ABI incompatibility. config UCLIBC_SUSV3_LEGACY_MACROS bool "Enable SuSv3 LEGACY macros" help Enable this option if you want to have SuSv3 LEGACY macros. Currently applies to bcopy/bzero/bcmp/index/rindex et al. WARNING! ABI incompatibility. config UCLIBC_SUSV4_LEGACY bool "Enable SuSv4 LEGACY or obsolescent functions" help Enable this option if you want to have SuSv4 LEGACY functions and macros in the library. Currently applies to: - XSI functions: _longjmp, _setjmp, _tolower, _toupper, ftw, getitimer, gettimeofday, isascii, pthread_getconcurrency, pthread_setconcurrency, setitimer, setpgrp, sighold, sigignore, sigpause, sigrelse, sigset, siginterrupt, tempnam, toascii, ulimit. - Base functions: asctime, asctime_r, ctime, ctime_r, gets, rand_r, tmpnam, utime. WARNING! ABI incompatibility. config UCLIBC_STRICT_HEADERS bool "Hide structures and constants for unsupported features" help Hide structures and constants in headers that should not be used, because the respective feature is disabled. WARNING! enabling this option requires to patch many faulty apps, since they make (wrongly) use of these structures/constants, although the feature was disabled. config UCLIBC_HAS_STUBS bool "Provide stubs for unavailable functionality" help With this option uClibc provides non-functional stubs for functions which are impossible to implement on the target architecture. Otherwise, such functions are simply omitted. config UCLIBC_HAS_SHADOW bool "Shadow Password Support" default y help Answer N if you do not need shadow password support. Most people will answer Y. config UCLIBC_HAS_PROGRAM_INVOCATION_NAME bool "Support for program_invocation_name" help Support for the GNU-specific program_invocation_name and program_invocation_short_name strings. Some GNU packages (like tar and coreutils) utilize these for extra useful output, but in general are not required. At startup, these external strings are automatically set up based on the value of ARGV[0]. If unsure, just answer N. config UCLIBC_HAS___PROGNAME bool "Support for __progname" default y depends on UCLIBC_HAS_PROGRAM_INVOCATION_NAME help Some packages (like openssh) like to peek into internal libc symbols to make their output a bit more user friendly. At startup, __progname is automatically set up based on the value of ARGV[0]. If unsure, just answer N. config UCLIBC_HAS_PTY bool "Support for pseudo-terminals" default y help This enables support for pseudo-terminals (see man 4 pts and man 7 pty). If unsure, just answer Y. config ASSUME_DEVPTS bool "Assume that /dev/pts is a devpts or devfs file system" default y depends on UCLIBC_HAS_PTY help Enable this if /dev/pts is on a devpts or devfs filesystem. Both these filesystems automatically manage permissions on the /dev/pts devices. You may need to mount your devpts or devfs filesystem on /dev/pts for this to work. Most people should answer Y. config UNIX98PTY_ONLY bool "Support only Unix 98 PTYs" default y depends on UCLIBC_HAS_PTY help If you want to support only Unix 98 PTYs enable this. Some older applications may need this disabled and will thus use legacy BSD style PTY handling which is more complex and also bigger than Unix 98 PTY handling. For most current programs, you can generally answer Y. if UNIX98PTY_ONLY config UCLIBC_HAS_GETPT bool "Support getpt() (glibc-compat)" depends on UCLIBC_HAS_PTY help Some packages may need getpt(). All of those are non-standard and can be considered GNU/libc compatibility. Either use posix_openpt() or just open /dev/ptmx yourself. If unsure, just say N. endif if !UNIX98PTY_ONLY # Have to use __libc_ptyname{1,2}[] and related bloat config UCLIBC_HAS_GETPT def_bool y endif config UCLIBC_HAS_LIBUTIL bool "Provide libutil library and functions" depends on UCLIBC_HAS_PTY help Provide a libutil library. This non-standard conforming library provides the following utility functions: forkpty(): combines openpty(), fork(2), and login_tty() to create a new process operating in a pseudo-terminal. login(): write utmp and wtmp entries login_tty(): prepares for a login on the tty fd by creating a new session, making fd the controlling terminal for the calling process, setting fd to be the standard input, output, and error streams of the current process, and closing fd. logout(): write utmp and wtmp entries logwtmp(): constructs a utmp structure and calls updwtmp() to append the structure to the utmp file. openpty(): finds an available pseudo-terminal and returns file descriptors for the master and slave This library adds about 3k-4k to your system. config UCLIBC_HAS_TM_EXTENSIONS bool "Support 'struct tm' timezone extension fields" default y help Enabling this option adds fields to 'struct tm' in time.h for tracking the number of seconds east of UTC, and an abbreviation for the current timezone. These fields are not specified by the SuSv3 standard, but they are commonly used in both GNU and BSD application code. To strictly follow the SuSv3 standard, leave this disabled. Most people will probably want to answer Y. config UCLIBC_HAS_TZ_CACHING bool "Enable caching of the last valid timezone 'TZ' string" default y help Answer Y to enable caching of the last valid 'TZ' string describing the timezone setting. This allows a quick string compare to avoid repeated parsing of unchanged 'TZ' strings when tzset() is called. Most people will answer Y. config UCLIBC_HAS_TZ_FILE bool "Enable '/etc/TZ' file support to set a default timezone (uClibc-specific)" default y help Answer Y to enable the setting of a default timezone for uClibc. Ordinarily, uClibc gets the timezone information exclusively from the 'TZ' environment variable. In particular, there is no support for the zoneinfo directory tree or the /etc/timezone file used by glibc. With this option enabled, uClibc will use the value stored in the file '/etc/TZ' (default path) to obtain timezone information if the 'TZ' environment variable is missing or has an invalid value. The file consists of a single line (newline required) of text describing the timezone in the format specified for the TZ environment variable. Doing 'echo CST6CDT > /etc/TZ' is enough to create a valid file. See http://www.opengroup.org/onlinepubs/007904975/basedefs/xbd_chap08.html for details on valid settings of 'TZ'. Most people will answer Y. config UCLIBC_HAS_TZ_FILE_READ_MANY bool "Repeatedly read the '/etc/TZ' file" depends on UCLIBC_HAS_TZ_FILE default y help Answer Y to enable repeated reading of the '/etc/TZ' file even after a valid value has been read. This incurs the overhead of an open/read/close for each tzset() call (explicit or implied). However, setting this will allow applications to update their timezone information if the contents of the file change. Most people will answer Y. config UCLIBC_TZ_FILE_PATH string "Path to the 'TZ' file for setting the global timezone" depends on UCLIBC_HAS_TZ_FILE default "/etc/TZ" help This is the path to the 'TZ' file. Most people will use the default of '/etc/TZ'. config UCLIBC_FALLBACK_TO_ETC_LOCALTIME bool "Use /etc/localtime as a fallback" depends on UCLIBC_HAS_TZ_FILE default y help Answer Y to try to use /etc/localtime file. On glibc systems this file (if it is in TZif2 format) contains timezone string at the end. Most people will answer Y. endmenu menu "Advanced Library Settings" config UCLIBC_PWD_BUFFER_SIZE int "Buffer size for getpwnam() and friends" default 256 range 12 1024 help This sets the value of the buffer size for getpwnam() and friends. By default, this is 256. (For reference, glibc uses 1024). The value can be found using sysconf() with the _SC_GETPW_R_SIZE_MAX parameter. config UCLIBC_GRP_BUFFER_SIZE int "Buffer size for getgrnam() and friends" default 256 range 12 1024 help This sets the value of the buffer size for getgrnam() and friends. By default, this is 256. (For reference, glibc uses 1024). The value can be found using sysconf() with the _SC_GETGR_R_SIZE_MAX parameter. comment "Support various families of functions" config UCLIBC_LINUX_MODULE_26 bool "Linux kernel module functions (2.6)" default y help delete_module, init_module are used in linux for loadable kernel modules. Say N if you do not use kernel modules. config UCLIBC_LINUX_MODULE_24 bool "Linux kernel module functions (<2.6)" depends on !TARGET_bfin && !TARGET_c6x help create_module, query_module are used in linux (prior to 2.6) for loadable kernel modules. Say N if you do not use kernel modules, or you only support Linux 2.6+. config UCLIBC_LINUX_SPECIFIC bool "Linux specific functions" default y help accept4(), bdflush(), capget(), capset(), eventfd(), fstatfs(), inotify_*(), ioperm(), iopl(), madvise(), modify_ldt(), pipe2(), personality(), prctl()/arch_prctl(), pivot_root(), modify_ldt(), ppoll(), readahead(), reboot(), remap_file_pages(), sched_getaffinity(), sched_setaffinity(), sendfile(), setfsgid(), setfsuid(), setresgid(), setresuid(), splice(), vmsplice(), tee(), signalfd(), swapoff(), swapon(), sync_file_range(), _sysctl(), sysinfo(), timerfd_*(), vhangup(), umount(), umount2() config UCLIBC_HAS_GNU_ERROR bool "Support GNU extensions for error-reporting" default y help Support for the GNU-specific error(), error_at_line(), void (* error_print_progname)(), error_message_count functions and variables. Some GNU packages utilize these for extra useful output, but in general are not required. If unsure, just answer N. config UCLIBC_BSD_SPECIFIC bool "BSD specific functions" default y help mincore(), getdomainname(), setdomainname() If unsure, say N. config UCLIBC_HAS_BSD_ERR bool "BSD err functions" default y help These functions are non-standard BSD extensions. err(), errx(), warn(), warnx(), verr(), verrx(), vwarn(), vwarnx() If unsure, say N. config UCLIBC_HAS_OBSOLETE_BSD_SIGNAL bool "BSD obsolete signal functions" help These functions are provided as a compatibility interface for programs that make use of the historical System V signal API. This API is obsolete: new applications should use the POSIX signal API (sigaction(2), sigprocmask(2), etc.). Affected functions: sigset(), sighold(), sigrelse(), sigignore() If unsure, say N. config UCLIBC_HAS_OBSOLETE_SYSV_SIGNAL bool "SYSV obsolete signal functions" help Use of sysv_signal() should be avoided; use sigaction(2) instead. If unsure, say N. config UCLIBC_NTP_LEGACY bool "ntp_*() aliases" help Provide legacy aliases for ntp functions: ntp_adjtime(), ntp_gettime() It is safe to say N here. config UCLIBC_SV4_DEPRECATED bool "Enable SVr4 deprecated functions" help These functions are DEPRECATED in System V release 4. Say N unless you desparately need one of the functions below: ustat() [use statfs(2) in your code instead] config UCLIBC_HAS_REALTIME bool "Realtime-related family of SUSv functions" default y help These functions are part of the Timers option and need not be available on all implementations. Includes AIO, message-queue, scheduler, semaphore functions: aio.h mqueue.h sched.h semaphore.h aio_cancel() aio_error() aio_fsync() aio_read() lio_listio() aio_return() aio_suspend() aio_write() clock_getres(), clock_gettime(), clock_settime() fdatasync() mlockall(), munlockall() mlock(), munlock() mq_close() mq_getattr() mq_notify() mq_open() mq_receive() mq_send() mq_setattr() mq_unlink() nanosleep() sched_getparam() sched_get_priority_max(), sched_get_priority_min() sched_getscheduler() sched_rr_get_interval() sched_setparam() sched_setscheduler() sem_close() sem_destroy() sem_getvalue() sem_init() sem_open() sem_post() sem_trywait(), sem_wait() sem_unlink() sigqueue() sigtimedwait(), sigwaitinfo() timer_create() timer_delete() timer_getoverrun(), timer_gettime(), timer_settime() config UCLIBC_HAS_ADVANCED_REALTIME bool "Advanced realtime-related family of SUSv functions" default y depends on UCLIBC_HAS_REALTIME help These functions are part of the Timers option and need not be available on all implementations. clock_getcpuclockid() clock_nanosleep() mq_timedreceive() mq_timedsend() posix_fadvise() posix_fallocate() posix_madvise() posix_memalign() posix_mem_offset() posix_spawnattr_destroy(), posix_spawnattr_init() posix_spawnattr_getflags(), posix_spawnattr_setflags() posix_spawnattr_getpgroup(), posix_spawnattr_setpgroup() posix_spawnattr_getschedparam(), posix_spawnattr_setschedparam() posix_spawnattr_getschedpolicy(), posix_spawnattr_setschedpolicy() posix_spawnattr_getsigdefault(), posix_spawnattr_setsigdefault() posix_spawnattr_getsigmask(), posix_spawnattr_setsigmask() posix_spawn_file_actions_addclose() posix_spawn_file_actions_adddup2() posix_spawn_file_actions_addopen() posix_spawn_file_actions_destroy() posix_spawn_file_actions_init() posix_spawn() posix_spawnp() posix_typed_mem_get_info() pthread_mutex_timedlock() sem_timedwait() #config UCLIBC_HAS_TERMIOS # bool "termios functions" # default y # help # Get and set terminal attributes, line control, get and set baud # rate. # termios(), tcgetattr(), tcsetattr(), tcsendbreak(), tcdrain(), # tcflush(), tcflow(), cfmakeraw(), cfgetospeed(), cfgetispeed(), # cfsetispeed(), cfsetospeed(), cfsetspeed() # # If unsure, say Y. config UCLIBC_HAS_EPOLL bool "epoll" default y help epoll_create(), epoll_ctl(), epoll_wait() functions. config UCLIBC_HAS_XATTR bool "Extended Attributes" default y help Extended Attributes support. setxattr() lsetxattr() fsetxattr() getxattr() lgetxattr() fgetxattr() listxattr() llistxattr() flistxattr() removexattr() lremovexattr() fremovexattr() Say N unless you need support for extended attributes and the filesystems do actually support them. config UCLIBC_HAS_PROFILING bool "Profiling support" default y help gcc's -finstrument-functions needs these. Most people can safely answer N. config UCLIBC_HAS_CRYPT_IMPL bool "libcrypt support" default y help libcrypt contains crypt(), setkey() and encrypt() config UCLIBC_HAS_SHA256_CRYPT_IMPL bool "libcrypt SHA256 support" depends on UCLIBC_HAS_CRYPT_IMPL help This adds support for SHA256 password hashing via the crypt() function. Say N here if you do not need SHA256 crypt support. config UCLIBC_HAS_SHA512_CRYPT_IMPL bool "libcrypt SHA512 support" depends on UCLIBC_HAS_CRYPT_IMPL help This adds support for SHA512 password hashing via the crypt() function. Say N here if you do not need SHA512 crypt support. config UCLIBC_HAS_CRYPT_STUB bool "libcrypt stubs" default y depends on !UCLIBC_HAS_CRYPT_IMPL help Standards mandate that crypt(3) provides a stub if it is unavailable. If you enable this option then stubs for crypt(), setkey() and encrypt() will be provided in a small libcrypt. config UCLIBC_HAS_CRYPT def_bool y depends on UCLIBC_HAS_CRYPT_IMPL || UCLIBC_HAS_CRYPT_STUB endmenu menuconfig UCLIBC_HAS_NETWORK_SUPPORT bool "Networking Support" default y help Say N here if you do not need network support. if UCLIBC_HAS_NETWORK_SUPPORT config UCLIBC_HAS_SOCKET bool "Socket support" default y help If you want to include support for sockets then answer Y. config UCLIBC_HAS_IPV4 bool "IP version 4 support" default y select UCLIBC_HAS_SOCKET help If you want to include support for the Internet Protocol (IP version 4) then answer Y. Most people will say Y. config UCLIBC_HAS_IPV6 bool "IP version 6 support" select UCLIBC_HAS_SOCKET help If you want to include support for the next version of the Internet Protocol (IP version 6) then answer Y. Most people should answer N. config UCLIBC_HAS_RPC bool "Remote Procedure Call (RPC) support" # RPC+socket-ipvX doesn't currently work. depends on UCLIBC_HAS_IPV4 || UCLIBC_HAS_IPV6 help If you want to include RPC support, enable this. RPC is rarely used for anything except for the NFS filesystem. Unless you plan to use NFS, you can probably leave this set to N and save some space. If you need to use NFS then you should answer Y. config UCLIBC_HAS_FULL_RPC bool "Full RPC support" depends on UCLIBC_HAS_RPC default y if !HAVE_SHARED help Normally we enable just enough RPC support for things like rshd and nfs mounts to work. If you find you need the rest of the RPC stuff, then enable this option. Most people can safely answer N. config UCLIBC_HAS_REENTRANT_RPC bool "Reentrant RPC support" depends on UCLIBC_HAS_RPC default y if !HAVE_SHARED help Most packages utilize the normal (non-reentrant) RPC functions, but some (like exportfs from nfs-utils) need these reentrant versions. Most people can safely answer N. config UCLIBC_USE_NETLINK bool "Use netlink to query interfaces" depends on UCLIBC_HAS_SOCKET help In newer versions of Linux (2.4.17+), support was added for querying network device information via netlink rather than the old style ioctl's. Most of the time, the older ioctl style is sufficient (and it is smaller than netlink), but if you find that not all of your devices are being returned by the if_nameindex() function, you will have to use the netlink implementation. Most people can safely answer N. config UCLIBC_SUPPORT_AI_ADDRCONFIG bool "Support the AI_ADDRCONFIG flag" depends on UCLIBC_USE_NETLINK help The implementation of AI_ADDRCONFIG is aligned with the glibc implementation using netlink to query interfaces to find both ipv4 and ipv6 support. This is only needed if an application uses the AI_ADDRCONFIG flag. Most people can safely answer N. config UCLIBC_HAS_BSD_RES_CLOSE bool "Support res_close() (bsd-compat)" help Answer Y if you desperately want to support BSD compatibility in the network code. Most people will say N. config UCLIBC_HAS_COMPAT_RES_STATE bool "Use compatible but bloated _res" default y help Answer Y if you build network utilities and they muck with resolver internals a lot (_res global structure). uclibc does not use most of _res.XXX fields, and with this option OFF they won't even exist. Which will make e.g. dig build fail. Answering N saves around 400 bytes in bss. config UCLIBC_HAS_EXTRA_COMPAT_RES_STATE bool "Use extra compatible but extra bloated _res" help Answer Y if selecting UCLIBC_HAS_COMPAT_RES_STATE is not enough. As far as I can say, this should never be needed. config UCLIBC_HAS_RESOLVER_SUPPORT bool "DNS resolver functions" select UCLIBC_HAS_COMPAT_RES_STATE depends on UCLIBC_HAS_IPV4 || UCLIBC_HAS_IPV6 help Provide implementations for DNS resolver functions. In particular, the following functions will be added to the library: ns_get16, ns_get32, ns_put16, ns_put32 config UCLIBC_HAS_LIBRESOLV_STUB bool "Provide libresolv stub" help Provide a dummy resolv library. config UCLIBC_HAS_LIBNSL_STUB bool "Provide libnsl stub" help Provide a dummy nsl library. endif menu "String and Stdio Support" config UCLIBC_HAS_STRING_GENERIC_OPT bool "Use faster (but larger) generic string functions" default y help Answer Y to use the (tweaked) glibc generic string functions. In general, they are faster (but 3-5K larger) than the base uClibc string functions which are optimized solely for size. Many people will answer Y. config UCLIBC_HAS_STRING_ARCH_OPT bool "Use arch-specific assembly string functions (where available)" default y help Answer Y to use any archtecture-specific assembly language string functions available for this target plaform. Note that assembly implementations are not available for all string functions, so some generic (written in C) string functions may still be used. These are small and fast, the only reason _not_ to say Y here is for debugging purposes. config UCLIBC_HAS_CTYPE_TABLES bool "Use Table Versions Of 'ctype.h' Functions." default y help Answer Y to use table versions of the 'ctype.h' functions. While the non-table versions are often smaller when building statically linked apps, they work only in stub locale mode. Most people will answer Y. config UCLIBC_HAS_CTYPE_SIGNED bool "Support Signed Characters In 'ctype.h' Functions." depends on UCLIBC_HAS_CTYPE_TABLES default y help Answer Y to enable support for passing signed char values to the 'ctype.h' functions. ANSI/ISO C99 and SUSv3 specify that these functions are only defined for unsigned char values and EOF. However, glibc allows negative signed char values as well in order to support 'broken old programs'. Most people will answer Y. choice prompt "ctype argument checking" depends on UCLIBC_HAS_CTYPE_TABLES default UCLIBC_HAS_CTYPE_UNSAFE help Please select the invalid arg behavior you want for the 'ctype' functions. The 'ctype' functions are now implemented using table lookups, with the arg being the index. This can result in incorrect memory accesses or even segfaults for args outside of the allowed range. NOTE: This only affects the 'ctype' _functions_. It does not affect the macro implementations. config UCLIBC_HAS_CTYPE_UNSAFE bool "Do not check -- unsafe" config UCLIBC_HAS_CTYPE_CHECKED bool "Detect and handle appropriately" config UCLIBC_HAS_CTYPE_ENFORCED bool "Issue a diagnostic and abort()" endchoice config UCLIBC_HAS_WCHAR bool "Wide Character Support" help Answer Y to enable wide character support. This will make uClibc much larger. It is also currently required for locale support. Most people will answer N. config UCLIBC_HAS_LOCALE bool "Locale Support" select UCLIBC_HAS_WCHAR select UCLIBC_HAS_CTYPE_TABLES help uClibc now has full ANSI/ISO C99 locale support (except for wcsftime() and collating items in regex). Be aware that enabling this option will make uClibc much larger. Enabling UCLIBC_HAS_LOCALE with the default set of supported locales (169 UTF-8 locales, and 144 locales for other codesets) will enlarge uClibc by around 300k. You can reduce this size by building your own custom set of locate data (see extra/locale/LOCALES for details). uClibc's locale support is still under development. For example, codesets using shift states are not currently supported. Support is planned in the next iteration of locale support. Answer Y to enable locale support. Most people will answer N. choice prompt "Locale data" depends on UCLIBC_HAS_LOCALE default UCLIBC_BUILD_ALL_LOCALE config UCLIBC_BUILD_ALL_LOCALE bool "All locales" depends on UCLIBC_HAS_LOCALE help This builds all the locales that are available on your host-box. config UCLIBC_BUILD_MINIMAL_LOCALE bool "Only selected locales" depends on UCLIBC_HAS_LOCALE help If you do not need all locales that are available on your host-box, then set this to 'Y'. config UCLIBC_PREGENERATED_LOCALE_DATA bool "Use Pre-generated Locale Data" depends on UCLIBC_HAS_LOCALE help Use pre-built locale data. Note that these pregenerated locales are sensitive to your target architecture (endianess, bitcount). Saying N here is highly recommended. endchoice config UCLIBC_BUILD_MINIMAL_LOCALES string "locales to use" depends on UCLIBC_BUILD_MINIMAL_LOCALE default "en_US" help Space separated list of locales to use. E.g.: en_US en_GB de_AT default: en_US config UCLIBC_DOWNLOAD_PREGENERATED_LOCALE_DATA bool "Automagically Download the Pre-generated Locale Data (if necessary)" depends on UCLIBC_PREGENERATED_LOCALE_DATA help If you would like the build process to use 'wget' to automatically download the pregenerated locale data, enable this option. Otherwise you will need to obtain the locale data yourself from: http://www.uclibc.org/downloads/uClibc-locale-*.tgz and place the uClibc-locale-*.tgz tarball in the extra/locale/ directory. Note that the use of pregenerated locale data is discouraged. config UCLIBC_HAS_XLOCALE bool "Extended Locale Support (experimental/incomplete)" depends on UCLIBC_HAS_LOCALE help Answer Y to enable extended locale support similar to that provided by glibc. This is primarily intended to support libstd++ functionality. However, it also allows thread-specific locale selection via uselocale(). Most people will answer N. config UCLIBC_HAS_HEXADECIMAL_FLOATS bool "Support hexadecimal float notation" depends on UCLIBC_HAS_CTYPE_TABLES depends on UCLIBC_HAS_FLOATS help Answer Y to enable support for hexadecimal float notation in the (wchar and) char string to floating point conversion functions, as well as support for the %a and %A conversion specifiers in the *printf() and *scanf() functions. Most people will answer N. config UCLIBC_HAS_GLIBC_DIGIT_GROUPING bool "Support glibc's \"'\" flag for allowing locale-specific digit grouping" depends on UCLIBC_HAS_LOCALE depends on UCLIBC_HAS_FLOATS help Answer Y to enable support for glibc's \"'\" flag for allowing locale-specific digit grouping in base 10 integer conversions and appropriate floating point conversions in the *printf() and *scanf() functions. Most people will answer N. config UCLIBC_HAS_SCANF_LENIENT_DIGIT_GROUPING bool "Do not require digit grouping when the \"'\" flag is specified" depends on UCLIBC_HAS_GLIBC_DIGIT_GROUPING default y help Answer Y to make digit grouping optional when the \"'\" flag is specified. This is the standard glibc behavior. If the initial string of digits exceeds the maximum group number, the input will be treated as a normal non-grouped number. Most people will answer N. config UCLIBC_HAS_GLIBC_CUSTOM_PRINTF bool "Support glibc's register_printf_function() (glibc-compat)" depends on !USE_OLD_VFPRINTF help Answer Y to support glibc's register_printf_function() to allow an application to add its own printf conversion specifiers. parse_printf_format() is also enabled. NOTE: Limits the number or registered specifiers to 10. NOTE: Requires new conversion specifiers to be ASCII characters (0-0x7f). This is to avoid problems with processing format strings in locales with different multibyte conversions. Most people will answer N. config USE_OLD_VFPRINTF bool "Use the old vfprintf implementation" depends on !UCLIBC_HAS_WCHAR help Set to true to use the old vfprintf instead of the new. This is roughly C89 compliant with some extensions, and is much smaller. However, it does not support wide chars, positional args, or glibc custom printf specifiers. Most people will answer N. config UCLIBC_PRINTF_SCANF_POSITIONAL_ARGS int "Maximum number of positional args. Either 0 or >= 9." depends on !USE_OLD_VFPRINTF default 9 help Set the maximum number of positional args supported by the printf/scanf functions. The Single Unix Specification Version 3 requires a minimum value of 9. Setting this to a value lower than 9 will disable positional arg support and cause the NL_ARGMAX macro in limits.h to be #undef'd. WARNING! The workspace to support positional args is currently allocated on the stack. You probably don't want to set this to too high a value. Most people will answer 9. choice prompt "Stdio buffer size" default UCLIBC_HAS_STDIO_BUFSIZ_4096 help Please select a value for BUFSIZ. This will be used by the stdio subsystem as the default buffer size for a file, and affects fopen(), setvbuf(), etc. NOTE: Setting this to 'none' will disable buffering completely. However, BUFSIZ will still be defined in stdio.h as 256 because many applications use this value. config UCLIBC_HAS_STDIO_BUFSIZ_NONE bool "none (WARNING - BUFSIZ will be 256 in stdio.h)" depends on !UCLIBC_HAS_WCHAR config UCLIBC_HAS_STDIO_BUFSIZ_256 bool "256 (minimum ANSI/ISO C99 value)" config UCLIBC_HAS_STDIO_BUFSIZ_512 bool "512" config UCLIBC_HAS_STDIO_BUFSIZ_1024 bool "1024" config UCLIBC_HAS_STDIO_BUFSIZ_2048 bool "2048" config UCLIBC_HAS_STDIO_BUFSIZ_4096 bool "4096" config UCLIBC_HAS_STDIO_BUFSIZ_8192 bool "8192" # If you add more choices, you will need to update uClibc_stdio.h. endchoice choice prompt "Stdio builtin buffer size (uClibc-specific)" depends on !UCLIBC_HAS_STDIO_BUFSIZ_NONE default UCLIBC_HAS_STDIO_BUILTIN_BUFFER_NONE help When a FILE is created with fopen(), an attempt is made to allocate a BUFSIZ buffer for it. If the allocation fails, fopen() will still succeed but the FILE will be unbuffered. This option adds a small amount of space to each FILE to act as an emergency buffer in the event of a buffer allocation failure. Most people will answer None. config UCLIBC_HAS_STDIO_BUILTIN_BUFFER_NONE bool "None" config UCLIBC_HAS_STDIO_BUILTIN_BUFFER_4 bool "4" config UCLIBC_HAS_STDIO_BUILTIN_BUFFER_8 bool "8" # If you add more choices, you will need to update uClibc_stdio.h. endchoice config UCLIBC_HAS_STDIO_SHUTDOWN_ON_ABORT bool "Attempt to shutdown stdio subsystem when abort() is called." help ANSI/ISO C99 requires abort() to be asyn-signal-safe. So there was a behavioral change made in SUSv3. Previously, abort() was required to have the affect of fclose() on all open streams. The wording has been changed to "may" from "shall". Most people will answer N. config UCLIBC_HAS_STDIO_GETC_MACRO bool "Provide a macro version of getc()" depends on !UCLIBC_HAS_STDIO_BUFSIZ_NONE default y help Provide a macro version of getc(). Most people will answer Y. config UCLIBC_HAS_STDIO_PUTC_MACRO bool "Provide a macro version of putc()" depends on !UCLIBC_HAS_STDIO_BUFSIZ_NONE default y help Provide a macro version of putc(). Most people will answer Y. config UCLIBC_HAS_STDIO_AUTO_RW_TRANSITION bool "Support auto-r/w transition" default y help Answer Y to enable the stdio subsystem to automaticly transition between reading and writing. This relaxes the ANSI/ISO C99 requirement: When a file is opened with update mode ('+' as the second or third character in the list of mode argument values), both input and output may be performed on the associated stream. However, output shall not be directly followed by input without an intervening call to the fflush function or to a file positioning function (fseek, fsetpos, or rewind), and input shall not be directly followed by output without an intervening call to a file positioning function, unless the input operation encounters end�of�file. Most people will answer Y. config UCLIBC_HAS_FOPEN_LARGEFILE_MODE bool "Support an fopen() 'F' flag for large file mode (uClibc-specific)" depends on UCLIBC_HAS_LFS help Answer Y to enable a uClibc-specific extension to allow passing an additional 'F' flag in the mode string for fopen() to specify that the file should be open()ed with the O_LARGEFILE flag set. Most people will answer N. config UCLIBC_HAS_FOPEN_EXCLUSIVE_MODE bool "Support an fopen() 'x' flag for exclusive mode (glibc-compat)" help Answer Y to support a glibc extension to allow passing additional 'x' flag in the mode string for fopen() to specify that the file should be open()ed with the O_EXCL flag set. Most people will answer N. config UCLIBC_HAS_FOPEN_CLOSEEXEC_MODE bool "Support an fopen() 'e' flag for close-on-exec mode (glibc-compat)" help Answer Y to support a glibc extension to allow passing additional 'e' flag in the mode string for fopen() to specify that the file should be open()ed with the O_CLOEXEC flag set. Most people will answer N. config UCLIBC_HAS_GLIBC_CUSTOM_STREAMS bool "Support fmemopen(), open_memstream(), and fopencookie() (glibc-compat)" help Answer Y to support the glibc 'custom stream' extension functions fmemopen(), open_memstream(), and fopencookie(). NOTE: There are some minor differences regarding seeking behavior. Most people will answer N. config UCLIBC_HAS_PRINTF_M_SPEC bool "Support the '%m' specifier in printf format strings (glibc-compat)" help Answer Y to support a glibc extension to interpret '%m' in printf format strings as an instruction to output the error message string (as generated by strerror) corresponding to the current value of 'errno'. Most people will answer N. config UCLIBC_HAS_ERRNO_MESSAGES bool "Include the errno message text in the library" default y help Answer Y if you want to include the errno message text in the library. This adds about 3K to the library, but enables strerror() to generate text other than 'Unknown error <number>'. Most people will answer Y. config UCLIBC_HAS_SYS_ERRLIST bool "Support sys_errlist[] (obsolete-compat)" depends on UCLIBC_HAS_ERRNO_MESSAGES help Answer Y if you want to support the obsolete sys_errlist[]. This adds about 0.5k to the library, except for the mips arch where it adds over 4K. WARNING! In the future, support for sys_errlist[] may be unavailable in at least some configurations. In fact, it may be removed altogether. Most people will answer N. Application writers: use the strerror(3) function. config UCLIBC_HAS_SIGNUM_MESSAGES bool "Include the signum message text in the library" default y help Answer Y if you want to include the signum message text in the library. This adds about 0.5K to the library, but enables strsignal() to generate text other than 'Unknown signal <number>'. Most people will answer Y. config UCLIBC_HAS_SYS_SIGLIST bool "Support sys_siglist[] (bsd-compat)" depends on UCLIBC_HAS_SIGNUM_MESSAGES help Answer Y if you want to support sys_siglist[]. WARNING! In the future, support for sys_siglist[] may be unavailable in at least some configurations. In fact, it may be removed altogether. Most people will answer N. config UCLIBC_HAS_GETTEXT_AWARENESS bool "Include gettext awareness" depends on UCLIBC_HAS_LOCALE && UCLIBC_MJN3_ONLY help NOTE!!! Not yet integrated with strerror and strsignal. NOTE!!! Answer Y if you want to include weak stub gettext support and make the *strerror*() and strsignal() functions gettext-aware. Currently, to get functional gettext functionality you will need to use gnu gettext. Most people will answer N. config UCLIBC_HAS_GNU_GETOPT bool "Support gnu getopt" default y help Answer Y if you want to include full gnu getopt() instead of a (much smaller) SUSv3 compatible getopt(). Most people will answer Y. config UCLIBC_HAS_STDIO_FUTEXES bool "Use futexes for multithreaded I/O locking" depends on UCLIBC_HAS_THREADS_NATIVE help If you want to compile uClibc to use futexes for low-level I/O locking, answer Y. Otherwise, answer N. config UCLIBC_HAS_GETOPT_LONG bool "Support getopt_long/getopt_long_only" depends on !UCLIBC_HAS_GNU_GETOPT default y help Answer Y if you want to include getopt_long[_only() used by many apps, even busybox. Most people will answer Y. config UCLIBC_HAS_GNU_GETSUBOPT bool "Support glibc getsubopt" default y help Answer Y if you want to include glibc getsubopt() instead of a smaller SUSv3 compatible getsubopt(). Most people will answer Y. endmenu menu "Big and Tall" config UCLIBC_HAS_REGEX bool "Regular Expression Support" default y help POSIX regular expression code is really big -- 53k all by itself. If you don't use regular expressions, turn this off and save space. Of course, if you only statically link, leave this on, since it will only be included in your apps if you use regular expressions. config UCLIBC_HAS_REGEX_OLD bool "Use the older (stable) regular expression code" depends on UCLIBC_HAS_REGEX default y help There are two versions of regex. The older (stable) version has been in uClibc for quite a long time but hasn't seen too many updates. It also has some known issues when dealing with uncommon corner cases and multibyte/unicode strings. However, it is quite a bit smaller than the newer version. If the older version has worked for you and you don't need unicode support, then stick with the old version (and say Y here). Otherwise, you should use the new version (and say N here). config UCLIBC_HAS_FNMATCH bool "fnmatch Support" default y help POSIX fnmatch. config UCLIBC_HAS_FNMATCH_OLD bool "Use the older (stable) fnmatch code" depends on UCLIBC_HAS_FNMATCH default y help There are two versions of fnmatch. The older (stable) version has been in uClibc for quite a long time but hasn't seen too many updates. It also has some known issues when dealing with uncommon corner cases and multibyte/unicode strings. However, it is quite a bit smaller than the newer version. If the older version has worked for you and you don't need unicode support, then stick with the old version (and say Y here). Otherwise, you should use the new version (and say N here). config UCLIBC_HAS_WORDEXP bool "Support the wordexp() interface" depends on UCLIBC_HAS_GLOB help The SuSv3 wordexp() interface performs word expansions per the Shell and Utilities volume of IEEE Std 1003.1-2001, Section 2.6. It is intended for use by applications that want to implement all of the standard Bourne shell expansions on input data. This interface is rarely used, and very large. Unless you have a pressing need for wordexp(), you should probably answer N. config UCLIBC_HAS_NFTW bool "Support the nftw() interface" help The SuSv3 nftw() interface is used to recursively descend directory paths while repeatedly calling a function. This interface is rarely used, and adds around 4.5k. Unless you have a pressing need for nftw(), you should probably answer N. config UCLIBC_HAS_FTW bool "Support the ftw() interface (SUSv4-obsolete)" depends on UCLIBC_SUSV4_LEGACY help The SuSv3 ftw() interface is used to recursively descend directory paths while repeatedly calling a function. This interface is rarely used, and adds around 4.5k. Unless you have a pressing need for ftw(), you should probably answer N. config UCLIBC_HAS_FTS bool "Support the fts() interface (bsd-compat)" help The fts functions are provided for traversing UNIX file hierarchies. This interface is currently used by the elfutils and adds around 7.5k. You should port your application to use the POSIX nftw() interface. Unless you need to build/use elfutils, you should prolly answer N. config UCLIBC_HAS_GLOB bool "Support the glob() interface" depends on UCLIBC_HAS_FNMATCH default y help The glob interface is somewhat large (weighing in at about 2,5k). It is used fairly often, but is an option since people wanting to go for absolute minimum size may wish to omit it. Most people will answer Y. config UCLIBC_HAS_GNU_GLOB bool "Support gnu glob() interface" depends on UCLIBC_HAS_GLOB help The gnu glob interface is somewhat larger (weighing in at about 4,2k) than it's SuSv3 counterpart (and is out of date). It is an old copy from glibc and does not support all the GNU specific options. Answer Y if you want to include full gnu glob() instead of the smaller SUSv3 compatible glob(). Most people will answer N. config UCLIBC_HAS_UTMPX bool "utmpx based support for tracking login/logouts to/from the system" help Answer y to enable support for accessing user accounting database. It can be used to track all login/logout to the system. If unsure, just answer N. endmenu menu "Library Installation Options" config RUNTIME_PREFIX string "uClibc runtime library directory" default "/usr/$(TARGET_ARCH)-linux-uclibc/" help RUNTIME_PREFIX is the directory into which the uClibc runtime libraries will be installed. The result will look something like the following: $(RUNTIME_PREFIX)/ lib/ <contains all runtime libraries> usr/bin/ldd <the ldd utility program> sbin/ldconfig <the ldconfig utility program> This value is used by the 'make install' Makefile target. Since this directory is compiled into the shared library loader, you will need to recompile uClibc if you change this value... For a typical target system this should be set to "/", such that 'make install' will install /lib/libuClibc-<VERSION>.so config DEVEL_PREFIX string "uClibc development environment directory" default "/usr/$(TARGET_ARCH)-linux-uclibc/usr/" help DEVEL_PREFIX is the directory into which the uClibc development environment will be installed. The result will look something like the following: $(DEVEL_PREFIX)/ lib/ <contains static libs> include/ <Where all the header files go> This value is used by the 'make install' Makefile target when installing a uClibc development environment. For a typical target system this should be set to "/usr", such that 'make install' will install /usr/include/<header files>. config MULTILIB_DIR string "library path component" default "lib" help Path component where libraries reside. For a typical target system this should be set to "lib", such that 'make install' will install libraries to "/lib" and "/usr/lib" respectively DEVEL_PREFIX/MULTILIB_DIR RUNTIME_PREFIX/MULTILIB_DIR Other settings may include "lib32" or "lib64". config HARDWIRED_ABSPATH bool "Hardwire absolute paths into linker scripts" default y help This prepends absolute paths to the libraries mentioned in linker scripts such as libc.so. This is a build time optimization. It has no impact on dynamic linking at runtime, which doesn't use linker scripts. You must disable this to use uClibc with old non-sysroot toolchains, such as the prebuilt binary cross compilers at: http://uclibc.org/downloads/binaries The amount of time saved by this optimization is actually too small to measure. The linker just had to search the library path to find the linker script, so the dentries are cache hot if it has to search the same path again. But it's what glibc does, so we do it too. endmenu menu "Security options" config UCLIBC_BUILD_PIE bool "Build utilities as ET_DYN/PIE executables" depends on HAVE_SHARED depends on TARGET_arm || TARGET_frv || TARGET_i386 || TARGET_mips || TARGET_powerpc select FORCE_SHAREABLE_TEXT_SEGMENTS help If you answer Y here, ldd and iconv are built as ET_DYN/PIE executables. It requires gcc-3.4 and binutils-2.15 (for arm 2.16) or later. More about ET_DYN/PIE binaries on <http://pax.grsecurity.net/> . WARNING: This option also enables FORCE_SHAREABLE_TEXT_SEGMENTS, so all libraries have to be built with -fPIC or -fpic, and all assembler functions must be written as position independent code (PIC). config UCLIBC_HAS_ARC4RANDOM bool "Include the arc4random() function" help Answer Y to support the OpenBSD-like arc4random() function. This function picks a random number between 0 and N, and will always return something even if the random driver is dead. If urandom fails then gettimeofday(2) will be used as the random seed. This function is designed to be more dependable than invoking /dev/urandom directly. OpenSSL and OpenNTPD currently support this function. Most people will answer N. config HAVE_NO_SSP bool config UCLIBC_HAS_SSP bool "Support for GCC stack smashing protector" depends on !HAVE_NO_SSP help Add code to support GCC's -fstack-protector[-all] option to uClibc. This requires GCC 4.1 or newer. GCC does not have to provide libssp, the needed functions are added to ldso/libc instead. GCC's stack protector is a reimplementation of IBM's propolice. See http://www.trl.ibm.com/projects/security/ssp/ and http://www.linuxfromscratch.org/hints/downloads/files/ssp.txt for details. Note that NOEXECSTACK on a kernel with address space randomization is generally sufficient to prevent most buffer overflow exploits without increasing code size. This option essentially adds debugging code to catch them. Most people will answer N. config UCLIBC_HAS_SSP_COMPAT bool "Support for gcc-3.x propolice smashing stack protector" depends on UCLIBC_HAS_SSP help Add gcc-3.x propolice smashing stack protector to the library. This requires a patched version of GCC, supporting the -fstack-protector[-all] options, with the __guard and __stack_smash_handler functions removed from libgcc. These functions are added to ldso/libc instead. More information at: <http://www.research.ibm.com/trl/projects/security/ssp/> Most people will answer N. config SSP_QUICK_CANARY bool "Use simple guard values without accessing /dev/urandom" depends on UCLIBC_HAS_SSP help Use gettimeofday(2) to define the __guard without accessing /dev/urandom. WARNING: This makes smashing stack protector vulnerable to timing attacks. Most people will answer N. choice prompt "Propolice protection blocking signal" depends on UCLIBC_HAS_SSP default PROPOLICE_BLOCK_ABRT if ! DODEBUG default PROPOLICE_BLOCK_SEGV if DODEBUG help "abort" use SIGABRT to block offending programs. This is the default implementation. "segfault" use SIGSEGV to block offending programs. Use this for debugging. If unsure, answer "abort". config PROPOLICE_BLOCK_ABRT bool "abort" config PROPOLICE_BLOCK_SEGV bool "segfault" endchoice config UCLIBC_BUILD_SSP bool "Build uClibc with -fstack-protector" depends on UCLIBC_HAS_SSP help Build all uClibc libraries and executables with -fstack-protector, adding extra stack overflow checking to most uClibc functions. config UCLIBC_BUILD_RELRO bool "Build uClibc with linker option -z RELRO" depends on HAVE_SHARED default y help Build all libraries and executables with "ld -z relro". This tells the linker to mark chunks of an executable or shared library read-only after applying dynamic relocations. (This comes up when a global const variable is initialized to the address of a function or the value of another global variable.) This is a fairly obscure option the ld man page doesn't even bother to document properly. It's a security paranoia issue that's more likely to consume memory (by allocating an extra page) rather than save it. This is explained in more depth at http://www.airs.com/blog/archives/189 Nobody is likely to care whether you say Y or N here. config UCLIBC_BUILD_NOW bool "Build uClibc with linker option -z NOW" depends on HAVE_SHARED help Build all libraries and executables with "ld -z now". This tells the linker to resolve all symbols when the library is first loaded, rather than when each function is first called. This increases start-up latency by a few microseconds and may do unnecessary work (resolving symbols that are never used), but the realtime people like it for making microbenchmark timings slightly more predictable and in some cases it can be slightly faster due to CPU cache behavior (not having to fault the linker back in to do lazy symbol resolution). Most people can't tell the difference between selecting Y or N here. config UCLIBC_BUILD_NOEXECSTACK bool "Build uClibc with noexecstack marking" default y help Mark all assembler files as noexecstack, which will mark uClibc as not requiring an executable stack. (This doesn't prevent other files you link against from claiming to need an executable stack, it just won't cause uClibc to request it unnecessarily.) This is a security thing to make buffer overflows harder to exploit. By itself, it's kind of useless, as Linus Torvalds explained in 1998: http://old.lwn.net/1998/0806/a/linus-noexec.html It only actually provides any security when combined with address space randomization, explained here: http://lwn.net/Articles/121845/ Address space randomization is on by default in current linux kernels (although it can be disabled using the option CONFIG_COMPAT_BRK). You should probably say Y. endmenu menu "Development/debugging options" config CROSS_COMPILER_PREFIX string "Cross-compiling toolchain prefix" default "" help The prefix used to execute your cross-compiling toolchain. For example, if you run 'arm-linux-uclibc-gcc' to compile something, then enter 'arm-linux-uclibc-' here. config UCLIBC_EXTRA_CFLAGS string "Extra CFLAGS" default "" help Add any additional CFLAGS to be used to build uClibc. config DODEBUG bool "Enable debugging symbols" select EXTRA_WARNINGS help Say Y here if you wish to compile uClibc with debugging symbols. This will allow you to use a debugger to examine uClibc internals while applications are running. This increases the size of the library considerably and should only be used when doing development. If you are doing development and want to debug uClibc, answer Y. Otherwise, answer N. config DODEBUG_PT bool "Build pthread with debugging output" depends on UCLIBC_HAS_THREADS && LINUXTHREADS_OLD help Enable debug output in libpthread. This is only useful when doing development in libpthread itself. Otherwise, answer N. config DOSTRIP bool "Strip libraries and executables" default y depends on !DODEBUG help Say Y here if you do wish to strip all uClibc libraries and executables. No stripping increases the size of the binaries considerably, but makes it possible to debug uClibc libraries. Most people will answer Y. config DOASSERTS bool "Build with run-time assertion testing" help Say Y here to include runtime assertion tests. This enables runtime assertion testing in some code, which can increase the size of the library and incur runtime overhead. If you say N, then this testing will be disabled. config SUPPORT_LD_DEBUG bool "Build the shared library loader with debugging support" depends on HAVE_SHARED help Answer Y here to enable all the extra code needed to debug the uClibc native shared library loader. The level of debugging noise that is generated depends on the LD_DEBUG environment variable... Just set LD_DEBUG to something like: 'LD_DEBUG=token1,token2,.. prog' to debug your application. Diagnostic messages will then be printed to the stderr. For now these debugging tokens are available: detail provide more information for some options move display copy processing symbols display symbol table processing reloc display relocation processing; detail shows the relocation patch nofixups never fixes up jump relocations bindings displays the resolve processing (function calls); detail shows the relocation patch all Enable everything! The additional environment variable: LD_DEBUG_OUTPUT=file redirects the diagnostics to an output file created using the specified name and the process id as a suffix. An excellent start is simply: $ LD_DEBUG=binding,move,symbols,reloc,detail ./appname or to log everything to a file named 'logfile', try this $ LD_DEBUG=all LD_DEBUG_OUTPUT=logfile ./appname If you are doing development and want to debug uClibc's shared library loader, answer Y. Mere mortals answer N. config SUPPORT_LD_DEBUG_EARLY bool "Build the shared library loader with early debugging support" depends on HAVE_SHARED help Answer Y here to if you find the uClibc shared library loader is crashing or otherwise not working very early on. This is typical only when starting a new port when you haven't figured out how to properly get the values for argc, argv, environ, etc. This method allows a degree of visibility into the very early shared library loader initialization process. If you are doing development and want to debug the uClibc shared library loader early initialization, answer Y. Mere mortals answer N. config UCLIBC_MALLOC_DEBUGGING bool "Build malloc with debugging support" depends on MALLOC || MALLOC_STANDARD help Answer Y here to compile extra debugging support code into malloc. Malloc debugging output may then be enabled at runtime using the MALLOC_DEBUG environment variable. The value of MALLOC_DEBUG should be an integer, which is interpreted as a bitmask with the following bits: 1 - do extra consistency checking 2 - output messages for malloc/free calls and OS allocation calls 4 - output messages for the `MMB' layer 8 - output messages for internal malloc heap manipulation calls Because this increases the size of malloc appreciably (due to strings etc), you should say N unless you need to debug a malloc problem. config UCLIBC_HAS_BACKTRACE bool "Add support for application self-debugging" depends on HAVE_SHARED help Answer Y here to compile support for application self-debugging, by adding a new shared object "libubacktrace.so" that provides the following new functions: backtrace, backtrace_symbols, backtrace_symbols_fd The backtrace functionality is currently supported on SH platform, and it based on dwarf2 informations to properly work, so any application that want to use backtrace needs to be built with -fexceptions flag. The symbol names may be unavailable without the use of special linker options. For systems using the GNU linker, it is necessary to use the -rdynamic linker option too. Note that names of "static" functions are not exposed, and won't be available in the backtrace. config WARNINGS string "Compiler Warnings" default "-Wall" help Set this to the set of compiler warnings you wish to see while compiling. config EXTRA_WARNINGS bool "Enable extra annoying warnings" help If you wish to build with extra warnings enabled, say Y here. config DOMULTI bool "Compile all sources at once into an object" help Set this to compile all sources at once into an object (IMA). This mode of compilation uses alot of memory but may produce smaller binaries. Note that you need a very recent GCC for this to work, like gcc >= 4.3 plus eventually some patches. If unsure, keep the default of N. config UCLIBC_MJN3_ONLY bool "Manuel's hidden warnings" help Answer Y here to see all Manuel's personal notes, warnings, and todos. Most people will answer N. endmenu