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Reserved bits in the Floating-Point Control and Status Register (FCSR) should not be implicitly cleared by fedisableexcept or feenableexcept, there is no reason to. Among these are the 8 condition codes and one of the two bits reserved for architecture implementers (bits #22 & #21). As to the latter, there is no reason to treat any of them as reserved either, they should be user controllable and settable via __fpu_control override as the user sees fit. For example in processors implemented by MIPS Technologies, such as the 5Kf or the 24Kf, these bits are used to change the treatment of denormalised operands and tiny results: bit #22 is Flush Override (FO) and bit #21 is Flush to Nearest (FN). They cause non-IEEE-compliant behaviour, but some programs may have a use for such modes of operation; the library should not obstruct such use just as it does not for the architectural Flush to Zero (FS) bit (bit #24). Therefore the change adjusts the reserved mask accordingly and also documents the distinction between bits 22:21 and 20:18. |
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| sysdeps | ||
| ChangeLog | ||
| ChangeLog.aarch64 | ||
| ChangeLog.aix | ||
| ChangeLog.alpha | ||
| ChangeLog.am33 | ||
| ChangeLog.arm | ||
| ChangeLog.cris | ||
| ChangeLog.hppa | ||
| ChangeLog.ia64 | ||
| ChangeLog.linux-generic | ||
| ChangeLog.m68k | ||
| ChangeLog.microblaze | ||
| ChangeLog.mips | ||
| ChangeLog.powerpc | ||
| ChangeLog.tile | ||
| README | ||
This is the glibc ports add-on, 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 add-on is cooperatively maintained by volunteers on the <libc-ports@sourceware.org> mailing list, and housed in the ports subdirectory of the glibc 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 add-on, please go to http://sourceware.org/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. 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., 2000-2013, indicating that every year in the range, inclusive, is a copyrightable year that would otherwise be listed individually.