# # For a description of the syntax of this configuration file, # see extra/config/Kconfig-language.txt # config HAVE_DOT_CONFIG bool default y menu "General Library Settings" config DOPIC bool "Generate Position Independent Code (PIC)" default y depends !HAVE_NO_PIC 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 HAVE_SHARED bool "Enable support for shared libraries" depends on DOPIC 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 ADD_LIBGCC_FUNCTIONS bool "Add unresolved libgcc symbols to uClibc" depends on HAVE_SHARED default n help If you answer Y here, all unresolved functions provided by the libgcc library that are used by uClibc will be added directly into the uClibc library. If your gcc compiler only provides a static libgcc library, then enabling this option can reduce the size of your binaries by preventing these functions from being staticly linked into every binary. If you have compiled uClibc as PIC code, one potential size effect of this option is that you may end up adding non-PIC libgcc code into your shared uClibc library, resulting in a non shareable text segment (thereby wasting a bunch of ram). If your compiler supports a shared libgcc library, you should certainly leave this option disabled. Regardless, the safest answer is N. config BUILD_UCLIBC_LDSO bool "Compile native shared library loader" depends on HAVE_SHARED default y help uClibc has a native shared library loader for some architectures. If you answer Y here, the uClibc native shared library loader will be built for your target architecture. If this option is available, to you, then you almost certainly want to answer Y. config FORCE_SHAREABLE_TEXT_SEGMENTS bool "Only load shared libraries which can share their text segment" depends on BUILD_UCLIBC_LDSO && UCLIBC_COMPLETELY_PIC && !ADD_LIBGCC_SYMBOLS default n 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). So 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 makes 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 shared library loader 'ldd' support" depends on BUILD_UCLIBC_LDSO default y help Enable this to 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 makes uClibc's shared library loader a little bit smaller. Most people will answer Y. 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 UCLIBC_PROFILING bool "Support gprof profiling" default y help If you wish to build uClibc with support for application profiling using the gprof tool, then you should enable this feature. Then in addition to building uClibc with profiling support, you will also need to recompile all your shared libraries with the profiling enabled version of uClibc. To add profiling support to your applications, you must compile things using the gcc options "-fprofile-arcs -pg". Then when you run your applications, a gmon.out file will be generated which can then be analyzed by 'gprof'. These exist a number of less invasive alternatives that do not require your to specially instrument your application, and recompile and relink everything. Many people have had good results using the combination of Valgrind to generate profiling information and KCachegrind for analysis: http://developer.kde.org/~sewardj/ http://kcachegrind.sourceforge.net/ The OProfile system-wide profiler is another alternative: http://oprofile.sourceforge.net/ Prospect is another alternative based on OProfile: http://prospect.sourceforge.net/ And the Linux Trace Toolkit (LTT) is also a fine tool: http://www.opersys.com/LTT/ If none of these tools do what you need, you can of course enable this option, rebuild everything, and use 'gprof'. There is both a size and performance penelty to profiling your applications this way, so most people should answer N. config UCLIBC_HAS_THREADS bool "POSIX Threading Support" default y 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. If your applications require pthreads, answer Y. config PTHREADS_DEBUG_SUPPORT bool "Build pthreads debugging support" default n 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_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-930716" 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. "malloc-930716" is derived from libc-5.3.12 and uses the brk() system call for all memory allocations. This makes it very fast. It is also pretty smart about reusing already allocated memory, and minimizing memory wastage. Because this uses brk() it will not work on uClinux MMU-less systems. If unsure, answer "malloc". config MALLOC bool "malloc" config MALLOC_930716 bool "malloc-930716" depends on UCLIBC_HAS_MMU endchoice 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 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_REGEX bool "Regular Expression Support" default y help POSIX regular expression code is really big -- 27k all by itself. If you don't use regular expressions, turn this off and save space. Of course, if you only staticly link, leave this on, since it will only be included in your apps if you use regular expressions. config UNIX98PTY_ONLY bool "Support only Unix 98 PTYs" default y help If you want to support only Unix 98 PTYs enable this. Some older applications may need this disabled. For most current programs, you can generally answer Y. config ASSUME_DEVPTS bool "Assume that /dev/pts is a devpts or devfs file system" default y 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 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. endmenu menu "Networking Support" config UCLIBC_HAS_IPV6 bool "IP version 6 Support" default n 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" default n 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. endmenu menu "String and Stdio Support" config UCLIBC_HAS_WCHAR bool "Wide Character Support" default n help Answer Y to enable wide character support. This will make uClibc much larger. Most people will answer N. config UCLIBC_HAS_LOCALE bool "Locale Support (experimental/incomplete)" depends on UCLIBC_HAS_WCHAR default n help Answer Y to enable locale support. This will make uClibc much bigger. uClibc's locale support is still under development, and should be finished in the next several weeks (November 2002). Most people will wisely answer N. config USE_OLD_VFPRINTF bool "Use the old vfprintf implementation" default n help Set to true to use the old vfprintf instead of the new. This is roughly C89 compliant, but doesn't deal with qualifiers on %n and doesn't deal with %h correctly or %hh at all on the integer conversions. But on i386 it is over 1.5k smaller than the new code. Of course, the new code fixes the above mentioned deficiencies and adds custom specifier support similar to glibc, as well as handling positional args. This will be rewritten at some point to bring it to full C89 standards compliance. Most people will answer N. endmenu menu "Library Installation Options" config SHARED_LIB_LOADER_PATH string "Shared library loader path" depends on BUILD_UCLIBC_LDSO default "$(DEVEL_PREFIX)/lib" help When using shared libraries, this path is the location where the shared library will be invoked. This value will be compiled into every binary compiled with uClibc. BIG FAT WARNING: If you do not have a shared library loader with the correct name sitting in the directory this points to, your binaries will not run. config SYSTEM_LDSO string "System shared library loader" depends on HAVE_SHARED && !BUILD_UCLIBC_LDSO default "/lib/ld-linux.so.2" help If you are using shared libraries, but do not want/have a native uClibc shared library loader, please specify the name of your target system's shared library loader here... BIG FAT WARNING: If you do not have a shared library loader with the correct name sitting in the directory this points to, your binaries will not run. config DEVEL_PREFIX string "uClibc development environment directory" default "/usr/$(TARGET_ARCH)-linux-uclibc" help DEVEL_PREFIX is the directory into which the uClibc development environment will be installed. The result will look something like the following: $(DEVEL_PREFIX)/ lib/ <contains all runtime and static libs> include/ <Where all the header files go> This value is used by the 'make install' Makefile target. Since this directory is compiled into the uclibc cross compiler spoofer, you have to recompile uClibc if you change this value... config SYSTEM_DEVEL_PREFIX string "uClibc development environment system directory" default "$(DEVEL_PREFIX)" help SYSTEM_DEVEL_PREFIX is the directory prefix used when installing bin/arch-uclibc-gcc, bin/arch-uclibc-ld, etc. This is only used by the 'make install' target, and is not compiled into anything. This defaults to $(DEVEL_PREFIX)/usr, but makers of .rpms and .debs will want to set this to "/usr" instead. config DEVEL_TOOL_PREFIX string "uClibc development environment tool directory" default "$(DEVEL_PREFIX)/usr" help DEVEL_TOOL_PREFIX is the directory prefix used when installing bin/gcc, bin/ld, etc. This is only used by the 'make install' target, and is not compiled into anything. This defaults to $(DEVEL_PREFIX)/usr, but makers of .rpms and .debs may want to set this to something else. endmenu menu "uClibc hacking options" config DODEBUG bool "Build uClibc with debugging symbols" default n 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 DOASSERTS bool "Build uClibc with run-time assertion testing" default n 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 BUILD_UCLIBC_LDSO default n 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 BUILD_UCLIBC_LDSO default n 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 MALLOC default n 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. Because this increases the size of malloc appreciably (due to strings etc), you should say N unless you need to debug a malloc problem. endmenu