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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!
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- 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 in
Glibc_vs_uClibc_Differences.txt, 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.
- 25 January 2003, dev system updates, arm image released
A number of additional problems have been fixed and the arm build
is now, finally, compiling and working as expected. As such,
I have updated the
i386 development system image, the
powerpc development system image, and I am also releasing
upon an unsuspecting world the brand new
arm development system image!
Have fun!
All three development system images were compiled and built using the stock
buildroot system. These were also
built using the (about to be announced in a couple on minutes) uClibc
0.9.17 release, so if you want to begin compiling and testing stuff with
uClibc, but you don't feel like spending the _hours_ it takes to download,
configure, and build your own uClibc based development system -- then you
may want to download these and give them a try. They each contain a 100 MB
ext2 filesystem with everything you need to begin compiling your own
applications. I have (at least minimally) tested each of them and verified
that the included gcc and g++ compilers produce working uClibc linked
executables.
Oh, and I have also have updated the uClibc/gcc toolchain builders, so
if you just want a simple uClibc/gcc toolchain,
one of these should work for you.
- 10 January 2003, dev system updates, powerpc image released
A few problems showed up in yesterday's development system release
(adduser was broken, gdb didn't work, libstdc++ shared libs were missing,
etc). So I've updated the
i386 development system image to fix these problems.
Also, the
powerpc development system image has finally finished compiling
and is now released upon an unsuspecting world. Have fun!
- 9 January 2003, uClibc development system released
CodePoet Consulting (i.e. Erik) has been working hard on buildroot recently, and is pleased to
offer a full stand-alone uClibc-only development system. This is an ext2
filesystem for i386 containing all the development software you need to
build your own uClibc applications. With bash, awk, make, gcc, g++,
autoconf, automake, ncurses, zlib, openssl, openssh, gdb, strace, valgrind,
busybox, GNU coreutils, and more, this should have pretty much everything
you need to get started building your own applications linked against
uClibc. By using a uClibc only system, you can avoid all the painful
cross-configuration problems that have made using uClibc somewhat painful
in the past. A powerpc and an arm version are in progress. Expect them
to be released shortly....
The
uClibc development system is an 18MB bzip2 compressed ext2 filesystem,
so be prepared to wait if you are on a slow link. If you wish to have more
space, you can loop mount it and 'cp -a' the contents to their own
partition, or do what I did... WARNING, the following can be very
dangerous. Please be sure you know what you are doing before trying this.
I am not responsible if you lose all your important data.I had a spare
hard drive (in my case /dev/hdg but you'll want to adapt this to your own
needs), so I partitioned it with a single ext2 partition filling the drive
(in my case /dev/hdg1). Then I ran:
bzcat root_fs_0.9.17-i386.bz2 | dd of=/dev/hdg1
e2fsck -f /dev/hdg1
resize2fs -p /dev/hdg1
which overwrote everything on /dev/hdg with the new uClibc devel system,
and then expanded the filesystem with the uClibc devel system till it
filled the whole drive.
- 8 November 2002, uClibc 0.9.16 Released
CodePoet Consulting is pleased to announce the immediate availability of
uClibc 0.9.16. This release adds full support (including a native shared
library loader) for the CRIS architecture, contributed by Tobias Anderberg.
Stefan Allius contributed a number of patches to fix the initialization
order for shared library global constructors and destructors as well as a
large number of SuperH fixes and cleanups. uClibc now compiles with
newer versions of gcc (i.e. RedHat 8.0). Thanks to Christian Michon,
uClibc no longer requires perl to compile. Steven J. Hill fixed dlopen for
mips. Several problems with pty and tty handling were fixed. Manuel Novoa
added new support for an /etc/TZ file to globally set the system timezone,
and fixed up a number of remaining wide char issues. Manuel is still hard
at work on bringing full locale support (optional of course) to uClibc.
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!
Erik and Manuel have been working on a
document describing some of the differences between uClibc and glibc.
It's not yet 100% complete, and it hasn't been nicely formatted yet. But
it contains a lot of helpful information and is worth a look.
And finally, the the old uClibc configuration system has been completely
removed (and there was much rejoicing). It was replaced with an entirely
new system based on LinuxKernelConf,
which has since been included into Linux 2.5.45, so it looks like Erik made
the right choice. Of course, those who have existing build systems using uClibc
will need to make a few changes... We think the change is worth it.
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.
Updated gcc-3.2 and gcc-2.95 toolchains will be released shortly.
- 16 September 2002, gcc-3.2 and gcc-2.95 toolchains released
CodePoet Consulting (i.e. Erik) has released updated gcc-3.2 and gcc-2.95
uClibc toolchains. These toolchains build real gcc cross compilers (i.e.
not just a wrapper) and create executables linked vs uClibc. The new
gcc-3.2 provides uClibc support with the latest and greatest compiler
available from the gcc team. The gcc-2.95 toolchain has been updated to
the latest version of uClibc and now provides full C++ support, using the
STLport standard C++ library.
This toolchain should make it easy for anyone to build uClibc based
applications.
Source code can be downloaded here.
Be aware that much of the needed source code will actually be downloaded on
when you compile the toolchains. To build a toolchain, simply
grab the source, edit the Makefile to select where you would like
the toolchain installed, run 'make', and then go watch TV, eat
dinner, or visit with your friends while it compiles. It takes
about 15 minutes for Erik to compile the gcc-3.2 toolchain (w/C++ support)
on his Athlon XP 1600 (not counting the time it takes to download
source code).
- Old News
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