| lh | 9ed821d | 2023-04-07 01:36:19 -0700 | [diff] [blame] | 1 | |
| 2 | uClibc - a Small C Library for Linux |
| 3 | Erik Andersen <andersen@codepoet.org> |
| 4 | |
| 5 | uClibc (aka µClibc/pronounced yew-see-lib-see) is a C library for |
| 6 | developing embedded Linux systems. It is much smaller than the |
| 7 | GNU C Library, but nearly all applications supported by glibc |
| 8 | also work perfectly with uClibc. Porting applications from glibc |
| 9 | to uClibc typically involves just recompiling the source code. |
| 10 | uClibc even supports shared libraries and threading. It currently |
| 11 | runs on standard Linux and MMU-less (also known as µClinux) |
| 12 | systems with support for alpha, ARM, cris, e1, h8300, i386, i960, |
| 13 | m68k, microblaze, mips/mipsel, PowerPC, SH, SPARC, and v850 |
| 14 | processors. |
| 15 | |
| 16 | If you are building an embedded Linux system and you find that |
| 17 | glibc is eating up too much space, you should consider using |
| 18 | uClibc. If you are building a huge fileserver with 12 Terabytes |
| 19 | of storage, then using glibc may make more sense. Unless, for |
| 20 | example, that 12 Terabytes will be Network Attached Storage and |
| 21 | you plan to burn Linux into the system's firmware... |
| 22 | |
| 23 | uClibc is maintained by Erik Andersen and is licensed under the |
| 24 | GNU LESSER GENERAL PUBLIC LICENSE. This license allows you to |
| 25 | make closed source commercial applications using an unmodified |
| 26 | version of uClibc (Please consider sharing some of the money you |
| 27 | make ;-). You do not need to give away all your source code just |
| 28 | because you use uClibc and/or run on Linux. You should, however, |
| 29 | carefuly review the license and make certain you understand and |
| 30 | abide by it strictly. |
| 31 | |
| 32 | |
| 33 | For installation instructions, see the file INSTALL. |
| 34 | |
| 35 | uClibc strives to be standards compliant, which means that most |
| 36 | documentation written for SuSv3, or for glibc also applies to |
| 37 | uClibc functions. However, many GNU extensions are not supported |
| 38 | because they have not been ported, or more importantly, would |
| 39 | increase the size of uClibc disproportional to the added |
| 40 | functionality. There is some discussion of these differences |
| 41 | in the "docs" directory. |
| 42 | |
| 43 | Additional information (recent releases, FAQ, mailing list, bugs, |
| 44 | etc.) can be found at http://www.uclibc.org/. |
| 45 | |
| 46 | uClibc may be freely modified and distributed under the terms of |
| 47 | the GNU Lesser General Public License, which can be found in the |
| 48 | file COPYING.LIB. |
| 49 | |
| 50 | Please Note: |
| 51 | |
| 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 |
| 63 | |
| 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: |
| 67 | |
| 68 | #ifdef __UCLIBC__ |
| 69 | do_something_special(); |
| 70 | #endif |
| 71 | |
| 72 | And most of all, be sure to have some fun! :-) |
| 73 | -Erik |