Re: PATCH: 1/6: Add AVX support

H.J. Lu
2010-03-05T02:06:21Z

On Thu, Mar 4, 2010 at 1:47 PM, Daniel Jacobowitz <dan@codesourcery.com> wrote:
> On Thu, Mar 04, 2010 at 01:27:09PM -0800, H.J. Lu wrote:
>> > No, it will fail to display SSE.  Core debugging should still be
>> > possible, and the newly added registers will be visible too.  If
>> > that's not the case, fix GDB to function with the SSE registers
>> > missing.
>>
>> Your description only works for truly NEW registers, which
>> AVX registers aren't.  AVX registers are actually the old SSE
>> registers with different names.
>
> I'm trying to get you to think about compatibility in the
> descriptions, instead of separately in the remote protocol.
> There are always ways to solve it.  For instance, you could present
> both the AVX registers and the hypothetical newer, larger registers as
> separate things.  As long as the P packet is implemented, which it is,
> GDB should work OK if modifying one register changes another.
> I don't know if there's an example of this in the GDB sources, but I
> have one in my tree; there's $sp, $sp_user, and $sp_system registers,
> and $sp is the same as one of the other two depending on processor
> mode.  But they're all visible.
>
> Another solution is to define new registers which correspond to the
> added bits, and have a sufficiently recent GDB synthesize the combined
> registers from the AVX registers and the new bits.  This, for
> instance, is how the Power E500 registers are handled
> (rs6000/power-spe.xml).
>

OK, I will try SPE approach. It will take a while.

Thanks.

--
H.J.