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authorPaul Mundt <lethal@linux-sh.org>2008-10-28 17:19:35 +0900
committerPaul Mundt <lethal@linux-sh.org>2008-10-28 17:19:35 +0900
commit8a2fd5f3ab6535035f08d7d0fda90abe73c6d282 (patch)
tree167165f7a6e27d0033787d83fbdc448d49527ad8 /arch/sh/configs/ul2_defconfig
parentMerge branch 'for-linus' of git://git.kernel.dk/linux-2.6-block (diff)
downloadlinux-dev-8a2fd5f3ab6535035f08d7d0fda90abe73c6d282.tar.xz
linux-dev-8a2fd5f3ab6535035f08d7d0fda90abe73c6d282.zip
sh: Fix FPU tuning on toolchains with mismatched multilib targets.
Presently there is very little standing in the way of using an SH-4 toolchain for building an SH-2 kernel, and vice versa. Binutils itself has no limitations whatsoever and supports explicit ISA hinting, which we already use with varying degrees of success today. This leaves GCC as the odd one out, due to a rather dubious policy decision by the GCC folks to not include all of the CPU family variants in the default list of multilib targets in GCC4. Despite best efforts to the contrary, libgcc itself already contains awareness of the various CPU types and remains generally usable, allowing it to safely be referenced even on a mismatched target (and indeed, explicit ISA tuning by binutils keeps us honest in terms of ensuring that we do not link incompatible objects in). In order to support this, a couple of changes had to be made. Firstly, the introduction of MAYBE_DECLARE_EXPORT(), which provides a __weak extern reference for libgcc resident routines when finer-grained -m<cpu-family> based tuning is not supported by the toolchain. This fixes up the __sdivsi3_i4i and __udivsi3_i4i references when dealing with SH-2 kernels linked with an SH-4 libgcc. Secondly, in case where we are unable to find a suitable match for CPU family tuning but still have a toolchain that defaults to FP instruction generation, a suitable nofpu target must be selected. This is accomplished by selecting the first nofpu multilib target supported by the toolchain, which is also necessary for selecting the proper libgcc to link against. Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Diffstat (limited to 'arch/sh/configs/ul2_defconfig')
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