µ C l i b c

uClibc -- a C library for embedded systems

uClibc (aka µClibc/pronounced yew-see-lib-see) is a C library for developing embedded Linux systems. It is much smaller than the GNU C Library, but nearly all applications supported by glibc also work perfectly with uClibc. Porting applications from glibc to uClibc typically involves just recompiling the source code. uClibc even supports shared libraries and threading. It currently runs on standard Linux and MMU-less (also known as µClinux) systems with support for alpha, ARM, i386, i960, h8300, m68k, mips/mipsel, PowerPC, SH, SPARC, and v850 processors.

If you are building an embedded Linux system and you find that glibc is eating up too much space, you should consider using uClibc. If you are building a huge fileserver with 12 Terabytes of storage, than using glibc may be a better choice...

uClibc is maintained by Erik Andersen and is licensed under the GNU LIBRARY GENERAL PUBLIC LICENSE . This license allows you to make closed source commercial applications using uClibc (Please consider sharing some of the money you make ;-). You do not need to give away all your source code just because you use uClibc and/or run on Linux.

### Mailing List Information

uClibc has a mailing list.
To subscribe, go and visit this page.

### Frequently Asked Questions

Before asking questions on the uClibc mailing list, you might want to take a look at the list of Frequently Asked Questions or you might want to search the mailing list archives... ...

### Working Applications List

These days, pretty much everything compiles with uClibc. This is a list of applications that are known to work just fine with uClibc. Since most applications work just fine with uClibc, we are especially interested in knowing about any applications that either do not compile or do not work properly with uClibc. Submissions are welcome!

Latest News

- 3 March 2003, uClibc 0.9.19 Released
  CodePoet Consulting is pleased to announce the immediate availability of uClibc 0.9.19. This is once again primarily a bug-fix release. Several critical problems with system calls were fixed, the pthreads library was improved, debugging of applications using uClibc's pthreads library is now possible (requires gdb 5.3 or newer that is compiled using uClibc), and a number of other random fixes are included. This release retains binary compatibility with uClibc 0.9.18 (except for mips, which didn't work properly with uClibc 0.9.18 anyways). Updated development systems images compiled with uClibc 0.9.19 will be released shortly.

  As usual, the Changelog and source code for this release are available here. You might want to download uClibc from the closest kernel.org mirror site. Just pick the closest mirror site, and then go to http://www.XX.kernel.org/pub/linux/libs/uclibc/ to download uClibc, where XX is your two letter country code.

- 17 February 2003, development system updates
  The uClibc development systems for i386 and powerpc, and arm have been again updated. This time around a few broken symlinks (one preventing C++ code from compiling) have been fixed, several system calls related to uids and gid have been fixed, the powerpc system call mechanism has been updated, and GNU tar and GNU grep have been added. gcc, gcc+, ssh, etc are all still included and things remain binary compatible with uClibc 0.9.18. Have Fun.

- 12 February 2003, development system updates
  The uClibc development system has had a number of problems fixed, and has been updated for uClibc 0.9.18. The i386 and powerpc, and arm devel systems are updated and ready to download and use. Have Fun.

- 12 February 2003, uClibc 0.9.18 Released
  CodePoet Consulting is pleased to announce the immediate availability of uClibc 0.9.18. This is primarily a bug-fix release, as there were a few directory handling problem that could cause application using uClibc 0.9.17 to either segfault or lose the first character when reading directry names. Unfortunately, once again, this release is _NOT_ binary compatible with earlier uClibc releases. I _think this will be the last time (with the possible exception of some future changes to our locale support...)

  As usual, the Changelog and source code for this release are available here. You might want to download uClibc from the closest kernel.org mirror site. Just pick the closest mirror site, and then go to http://www.XX.kernel.org/pub/linux/libs/uclibc/ to download uClibc, where XX is your two letter country code.

- 25 January 2003, uClibc 0.9.17 Released
  CodePoet Consulting is pleased to announce the immediate availability of uClibc 0.9.17. The biggest piece of news with this release, thanks to Manuel Novoa's continuing hard work, is that we now have fully standards compliant locale support (optional of course). The support works nicely, (though configuring the locales you wish to support is still manual -- a task for the next release). Full locale data for over 300 locales adds approximately 250k. The collation data for all supported locales is roughly 180k. This may seem rather large to some -- but it is much smaller than the approximately 40 MB needed by Glibc to provide the same data. And if you don't need it, you can either disable locale support entirely, or enable a smaller set of locales.

  This release also fixes lots and lots of bugs. The arm architecture support (I am embarrassed to note) was totally broken in the last release, but is now working as expected. A security problem (a buffer overflow in getlogin_r) was fixed. And there were architecture updates across the board (x86, arm, powerpc, cris, h8300, sparc, and mips). And of course, this release includes the usual pile of bug fixes. Many thanks for the large number of patches and fixes that were contributed!

  Unfortunately, this release is not binary compatible with earlier uClibc releases. As noted as item 3 here, uClibc does not (yet) attempt to ensure binary compatibility across releases. We will eventually do that (once we reach the "1.0" release) but not yet. A few bugs turned up that needed to be fixed, and the only good way to fix them was to change some fundamental data structure sizes. As a result, this release is _NOT_ binary compatible with earlier releases -- you will need to recompile your applications. The x86, arm, powerpc, and mips architectures (i.e. the systems Erik has available in his office for testing) have been tested and are known to work following this change. Other architectures may need additional updates. Sorry about that, but it had to be done.

  As usual, the Changelog and source code for this release are available here. You might want to download uClibc from the closest kernel.org mirror site. Just pick the closest mirror site, and then go to http://www.XX.kernel.org/pub/linux/libs/uclibc/ to download uClibc, where XX is your two letter country code.

- Old News
  Click here to read older news.

Sponsors

Please visit our sponsors and thank them for their support! They have provided money, equipment, bandwidth, etc. Next time you need help with a project, consider these fine companies! Several individuals have also contributed (If you have contributed and would like your name added here, just email Erik and let him know).

- Penguru Consulting
  Custom development for embedded Linux systems and multimedia platforms
- opensource.se
  Embedded open source consulting in Europe.
- Codepoet Consulting
  Custom Linux, embedded Linux, BusyBox, and uClibc development.

Do you like uClibc? Do you need support? Do you need some feature added? Then why not help out? We are happy to accept donations (such as bandwidth, mirrors sites, and hardware for the various architectures). We can also provide support contracts, and implement funded feature requests. To contribute, you can either click on the Donate image to donate using PayPal, or you can contact Erik at CodePoet Consulting (we have a credit card machine so you can avoid PayPal if you wish).

Download

- Source for the latest release can always be downloaded from http://www.uclibc.org/downloads
- A daily snapshot of the source is available for those wishing to follow uClibc developments, but cannot or do not wish to use CVS.
- uClibc has a publically browsable CVS tree.
- Anonymous CVS access is available to let you track development.
- CVS write access is also available for those that are actively contributing.

Toolchains

- Steven J. Hill has kindly provided RPMs and SRPMs with toolchains for mips.
- You can build your own uClibc toolchain using these Makefiles which automagically download all the source needed code and compile it for you.
- uClibc development systems for i386 and powerpc, and arm are available and contain complete gcc 3.2.2 toolchains.
- You can compile your own uClibc development system using buildroot.

Other Open Source C libraries:

I am currently aware of the following open source C libraries.

- GNU C Library (aka glibc)
- Al's FREE C Runtime Library
- diet libc
- the minix C library
- newlib
- and there is a C library, for eCos as well.

Links to other useful stuff

- The uClibc home page

- The uClibc CVS tree

- BusyBox

- udhcp

- The uClinux home page

- The uClinux CVS repository

- CodePoet Consulting

Mail all comments, insults, suggestions and bribes to Erik Andersen |  |  |  |  |