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Diffstat (limited to 'gcc/doc/fragments.texi')
| -rw-r--r-- | gcc/doc/fragments.texi | 31 |
1 files changed, 24 insertions, 7 deletions
diff --git a/gcc/doc/fragments.texi b/gcc/doc/fragments.texi index f9ef3d22b82..c9ebcf9145d 100644 --- a/gcc/doc/fragments.texi +++ b/gcc/doc/fragments.texi @@ -1,5 +1,5 @@ @c Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998, -@c 1999, 2000, 2001 Free Software Foundation, Inc. +@c 1999, 2000, 2001, 2003 Free Software Foundation, Inc. @c This is part of the GCC manual. @c For copying conditions, see the file gcc.texi. @@ -134,12 +134,12 @@ specified, there are combinations that should not be built. In that case, set @code{MULTILIB_EXCEPTIONS} to be all of the switch exceptions in shell case syntax that should not be built. -For example, in the PowerPC embedded ABI support, it is not desirable -to build libraries compiled with the @option{-mcall-aix} option -and either of the @option{-fleading-underscore} or @option{-mlittle} options -at the same time. Therefore @code{MULTILIB_EXCEPTIONS} is set to +For example the ARM processor cannot execute both hardware floating +point instructions and the reduced size THUMB instructions at the same +time, so there is no need to build libraries with both of these +options enabled. Therefore @code{MULTILIB_EXCEPTIONS} is set to: @smallexample -*mcall-aix/*fleading-underscore* *mlittle/*mcall-aix* +*mthumb/*mhard-float* @end smallexample @findex MULTILIB_EXTRA_OPTS @@ -147,7 +147,24 @@ at the same time. Therefore @code{MULTILIB_EXCEPTIONS} is set to Sometimes it is desirable that when building multiple versions of @file{libgcc.a} certain options should always be passed on to the compiler. In that case, set @code{MULTILIB_EXTRA_OPTS} to be the list -of options to be used for all builds. +of options to be used for all builds. If you set this, you should +probably set @code{CRTSTUFF_T_CFLAGS} to a dash followed by it. + +@findex SPECS +@item SPECS +Unfortunately, setting @code{MULTILIB_EXTRA_OPTS} is not enough, since +it does not affect the build of target libraries, at least not the +build of the default multilib. One possible work-around is to use +@code{DRIVER_SELF_SPECS} to bring options from the @file{specs} file +as if they had been passed in the compiler driver command line. +However, you don't want to be adding these options after the toolchain +is installed, so you can instead tweak the @file{specs} file that will +be used during the toolchain build, while you still install the +original, built-in @file{specs}. The trick is to set @code{SPECS} to +some other filename (say @file{specs.install}), that will then be +created out of the built-in specs, and introduce a @file{Makefile} +rule to generate the @file{specs} file that's going to be used at +build time out of your @file{specs.install}. @end table @node Host Fragment |