2 uClibc - a Small C Library for Linux
3 Erik Andersen <email@example.com>
5uClibc (aka �Clibc/pronounced yew-see-lib-see) is a C library for
6developing embedded Linux systems. It is much smaller than the
7GNU C Library, but nearly all applications supported by glibc
8also work perfectly with uClibc. Porting applications from glibc
9to uClibc typically involves just recompiling the source code.
10uClibc even supports shared libraries and threading. It currently
11runs on standard Linux and MMU-less (also known as �Clinux)
12systems with support for alpha, ARM, cris, e1, h8300, i386, i960,
13m68k, microblaze, mips/mipsel, PowerPC, SH, SPARC, and v850
16If you are building an embedded Linux system and you find that
17glibc is eating up too much space, you should consider using
18uClibc. If you are building a huge fileserver with 12 Terabytes
19of storage, then using glibc may make more sense. Unless, for
20example, that 12 Terabytes will be Network Attached Storage and
21you plan to burn Linux into the system's firmware...
23uClibc is maintained by Erik Andersen and is licensed under the
24GNU LESSER GENERAL PUBLIC LICENSE. This license allows you to
25make closed source commercial applications using an unmodified
26version of uClibc (Please consider sharing some of the money you
27make ;-). You do not need to give away all your source code just
28because you use uClibc and/or run on Linux. You should, however,
29carefuly review the license and make certain you understand and
30abide by it strictly.
33For installation instructions, see the file INSTALL.
35uClibc strives to be standards compliant, which means that most
36documentation written for SuSv3, or for glibc also applies to
37uClibc functions. However, many GNU extensions are not supported
38because they have not been ported, or more importantly, would
39increase the size of uClibc disproportional to the added
40functionality. There is some discussion of these differences
41in the "docs" directory.
43Additional information (recent releases, FAQ, mailing list, bugs,
44etc.) can be found at http://www.uclibc.org/.
46uClibc may be freely modified and distributed under the terms of
47the GNU Lesser General Public License, which can be found in the
52 There is an unwholesomely huge amount of code out there
53 that depends on the presence of GNU libc header files.
54 We have GNU libc compatible header files. So we have
55 committed a horrible sin in uClibc. We _lie_ and claim
56 to be GNU libc in order to force these applications to
57 work as their developers intended. This is IMHO,
58 pardonable, since these defines are not really intended
59 to check for the presence of a particular library, but
60 rather are used to define an _interface_. Some programs
61 are especially chummy with glibc, and may need this
62 behavior disabled by adding CFLAGS+=-D__FORCE_NOGLIBC
64 If you want to make special exceptions in your code which are
65 specifically for uClibc, you can make certain to include features.h,
66 and then have your code check for uClibc as follows:
68 #ifdef __UCLIBC__
72And most of all, be sure to have some fun! :-)