Re: PATCH: 1/6: Add AVX support

[Daniel Jacobowitz <dan@codesourcery.com>]

On Thu, Mar 04, 2010 at 11:29:38AM -0800, H.J. Lu wrote:
> AVX registers aren't new registers, on top of SSE registers. AVX
> registers are the super set of SSE registers. XMM0 is the alias
> of the lower 128bit of YMM0. So we have either SSE target or
> AVX target, depending on the processor/OS. We may have
> remote gdb stub on an AVX processor/OS.  But gdb, which
> the stub is talking to, may not support AVX at all. If the stub
> sends the AVX target description to gdb, gdb won't understand it
> and will fail.

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.

The goal of the target description language is to communicate the
entire target to GDB.  If you're not putting enough in the description
for an arbitrary XML-capable GDB to function, then you need to rethink
how you've written the description.

I do not think that having GDB negotiate with the target for an
intermediate target description is a good idea.  Also, it is not hard
to upgrade GDB on the host.  It can be hard to upgrade the target, of
course.

-- 
Daniel Jacobowitz
CodeSourcery