Re: PATCH: Extend gdb remote protocol for AVX

Daniel Jacobowitz
2008-10-04T22:14:10Z

On Sat, Oct 04, 2008 at 10:49:03PM +0200, Mark Kettenis wrote:
> If there would be a desire on amd64 to be able to refer to the 32-bit
> parts of the general-purpose registers we would implement them in much
> the same way as I propose for %xmm/%ymm, as pseudo registers.

FWIW I think we should do this. It confuses me sometimes that
instructions get disassembled refering to %eax, but print $eax does
not work. It just hasn't confused me enough to fix it yet.

> I have no objection to the changes you proposed for the remote
> protocol. But your diff also touches the core register stuff, and
> that needs a bit more thought to make sure we don't surprise our
> users. At that point, it may be easier to use the same model for the
> remote protocol, where you transfer the top 128 bits of the %ymm
> registers in addition to the %xmm registers. Adter all this is how
> the hardware does it too (xsave is just an extension of fxsave).

One way would be to transfer the xmm registers and then the remaining
bits as unnamed registers; another, probably easier way would be to
use an architecture specification or an actual register description to
transfer just the ymm registers and let GDB know about that fact, so
it can synthesize the xmm registers.

(I don't remember the original patch, that may be what you're talking
about already.)

--
Daniel Jacobowitz
CodeSourcery