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With gcc 4.8 tilegx has support for -mcmodel=large, to tolerate very large shared objects. This option changes the compiler output to not include direct jump instructions, which have a range of only 2^30, i.e +/- 512MB. Instead the compiler marshalls the target PCs into registers and then uses jump- or call-to-register instructions. For glibc, the upshot is that we need to arrange for a few functions to tolerate the possibility of a large range between the PC and the target. In particular, the crti.S and start.S code needs to be able to reach from .init to the PLT, as does gmon-start.c. The elf-init.c code has the reverse problem, needing to call from libc_nonshared.a (linked at the end of shared objects) back to the _init section at the beginning. No other functions in *_nonshared.a need to be built this way, as they only call the PLT (or potentially each other), but all of that code is linked at the very end of the shared object. We don't build the standard -static archives with this option as the performance cost is high enough and the use case is rare enough that it doesn't seem worthwhile. Instead, we would encourage developers who need the -static model with huge executables to build a private copy of glibc and configure it with -mcmodel=large. Note that libc.so et al don't need any changes; the only changes are for code that is statically linked into user code built with -mcmodel=large. For the assembly code, I just rewrote it so that it unconditionally uses the large model. To be able to pass -mcmodel=large to csu/elf-init.c and csu/gmon-start.c, I need to check to see if the compiler supports that flag, since gcc 4.7 doesn't; I added the support by creating a small Makefile fragment that just runs the compiler to check. |
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| sysdeps | ||
| ChangeLog | ||
| ChangeLog.aix | ||
| ChangeLog.alpha | ||
| ChangeLog.am33 | ||
| ChangeLog.arm | ||
| ChangeLog.cris | ||
| ChangeLog.hppa | ||
| ChangeLog.ia64 | ||
| ChangeLog.linux-generic | ||
| ChangeLog.m68k | ||
| ChangeLog.mips | ||
| ChangeLog.powerpc | ||
| ChangeLog.tile | ||
| README | ||
This is the glibc ports repository, an add-on for the GNU C Library (glibc). It contains code that is not maintained in the official glibc source tree. This includes working ports to GNU/Linux on some machine architectures that are not maintained in the official glibc source tree. It also includes some code once used by old libc ports now defunct, which has been abandoned but may be useful for some future porter to examine. It may also include some optimized functions tailored for specific CPU implementations of an architecture, to be selected using --with-cpu. The ports repository is cooperatively maintained by volunteers on the <libc-ports@sourceware.org> mailing list, and housed in a separate ports git repository. See http://www.gnu.org/software/libc/download.html for details on using git. To report a bug in code housed in the ports repository, please go to http://sources.redhat.com/bugzilla/ and file a bug report under the glibc "ports" component. An add-on for an individual port can be made from just the sysdeps/ subdirectories containing the port's code. You may want to include a README and Banner of your own talking about your port's code in particular, rather than the generic ones here. The real source code for any ports is found in the sysdeps/ subdirectories. These should be exactly what would go into the main libc source tree if you were to incorporate it directly. The only exceptions are the files sysdeps/*/preconfigure and sysdeps/*/preconfigure.in; these are fragments used by this add-on's configure fragment. The purpose of these is to set $base_machine et al when the main libc configure's defaults are not right for some machine. Everything else can and should be done from a normal sysdeps/.../configure fragment that is used only when the configuration selects that sysdeps subdirectory. Each port that requires some special treatment before the sysdeps directory list is calculated, should add a sysdeps/CPU/preconfigure file; this can either be written by hand or generated by Autoconf from sysdeps/CPU/preconfigure.in, and follow the rules for glibc add-on configure fragments. No preconfigure file should do anything on an unrelated configuration, so that disparate ports can be put into a single add-on without interfering with each other. Files that would go in scripts/data/ for libc go in data/ in ports. Like all glibc add-ons, this must be used by specifying the directory in the --enable-add-ons option when running glibc's configure script. The GNU C Library is free software. See the file COPYING.LIB in the libc repository for copying conditions, and LICENSES for notices about a few contributions that require these additional notices to be distributed. License copyright years may be listed using range notation, e.g., 2000-2011, indicating that every year in the range, inclusive, is a copyrightable year that would otherwise be listed individually.