svn commit: r216977 - in head/libexec/rtld-elf: amd64 i386

John Baldwin jhb at
Wed Jan 5 14:38:41 UTC 2011

On Wednesday, January 05, 2011 8:36:06 am Dimitry Andric wrote:
> On 2011-01-05 13:59, John Baldwin wrote:
> >> Why not to add NO_HWFLOAT knob (or similar) into makefile
> >> infrastructure. And set CFLAGS accordingly, depending on CC, arch, etc.
> >> These flags are getting rather common in tree.
> >
> > It strikes me that we really want clang/gcc to have some sort of
> > '-mno-hwfloat' so we don't keep having to add new flags in the future.
> This is not just about floats, clang can also use SSE/AVX instructions
> for e.g.  memset(), memcpy() and the like, or even for structure
> assignments.

Yes, but the thing that all these extensions have in common is that they use
FPU state (i.e. subject to DNA traps, managed via *SAVE and *RSTOR, etc.)
and that is the problem with using them in boot code or rtld.  What I would
want a -mno-hwfloat flag to do is to disable use of anything that would
require working FPU state handling.

John Baldwin

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