On Mon, May 19, 2008 at 09:29:01AM -0700, H. Peter Anvin wrote:
OSXSAVE indicates the OS support and XSAVE indicates the cpu support.
There might be some old applications, which just care about FP/SSE and
just check for 0xffff (plain) or 0x0000 (fxsr). We should extend this
in a backward compatible manner.
All the reserved fields at the end of fxsave format are zeroed and
presented as such to the user. If HW makes some of these fields SW available,
then we can use those (will check). If there is any scope with the
existing format it self, that will be much better.