path: root/INSTALL
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authorJoseph Myers <joseph@codesourcery.com>2017-12-12 13:56:47 +0000
committerJoseph Myers <joseph@codesourcery.com>2017-12-12 13:56:47 +0000
commit8df5d34720dd71e934545bade879e04697830757 (patch)
treeaf607d1b63037ad92901e4ed8a4a71f95270ee31 /INSTALL
parent0cee1257a96fc2983c7cc0717015ad54d81ceff3 (diff)
Remove --with-fp / --without-fp.
There is a configure option --without-fp that specifies that nofpu sysdeps directories should be used instead of fpu directories. For most glibc configurations, this option is of no use: either there is no valid nofpu variant of that configuration, or there are no fpu or nofpu sysdeps directories for that processor and so the option does nothing. For a few configurations, if you are using a soft-float compiler this option is required, and failing to use it generally results in compilation errors from inline asm using unavailable floating-point instructions. We're moving away from --with-cpu to configuring glibc based on how the compiler generates code, and it is natural to do so for --without-fp as well; in most cases the soft-float and hard-float ABIs are incompatible so you have no hope of building a working glibc with an inappropriately configured compiler or libgcc. This patch eliminates --without-fp, replacing it entirely by automatic configuration based on the compiler. Configurations for which this is relevant (coldfire / mips / powerpc32 / sh) define a variable with_fp_cond in their preconfigure fragments (under the same conditions under which those fragments do anything); this is a preprocessor conditional which the toplevel configure script then uses in a test to determine which sysdeps directories to use. The config.make with-fp variable remains. It's used only by powerpc (sysdeps/powerpc/powerpc32/Makefile) to add -mhard-float to various flags variables. For powerpc, -mcpu= options can imply use of soft-float. That could be an issue if you want to build for e.g. 476fp, but are using --with-cpu=476 because there isn't a 476fp sysdeps directory. If in future we eliminate --with-cpu and replace it entirely by testing the compiler, it would be natural at that point to eliminate that code as well (as the user should then just use a compiler defaulting to 476fp and the 476 sysdeps directory would be used automatically). Tested for x86_64, and tested with build-many-glibcs.py that installed shared libraries are unchanged by this patch. * configure.ac (--with-fp): Remove configure option. (with_fp_cond): New variable. (libc_cv_with_fp): New configure test. Use this variable instead of with_fp. * configure: Regenerated. * config.make.in (with-fp): Use @libc_cv_with_fp@. * manual/install.texi (Configuring and compiling): Remove --without-fp. * INSTALL: Regenerated. * sysdeps/m68k/preconfigure (with_fp_cond): Define for ColdFire. * sysdeps/mips/preconfigure (with_fp_cond): Define. * sysdeps/powerpc/preconfigure (with_fp_cond): Define for 32-bit. * sysdeps/sh/preconfigure (with_fp_cond): Define. * scripts/build-many-glibcs.py (Context.add_all_configs): Do not use --without-fp to configure glibc.
Diffstat (limited to 'INSTALL')
1 files changed, 0 insertions, 4 deletions
diff --git a/INSTALL b/INSTALL
index e59c11dabdf..80306de35c5 100644
@@ -81,10 +81,6 @@ will be used, and CFLAGS sets optimization options for the compiler.
library will still be usable, but functionality may be lost--for
example, you can't build a shared libc with old binutils.
- Use this option if your computer lacks hardware floating-point
- support and your operating system does not emulate an FPU.
Don't build shared libraries even if it is possible. Not all
systems support shared libraries; you need ELF support and