Re: [PATCH] i386: Use a fallback XSAVE layout for remote targets

[John Baldwin <jhb@FreeBSD.org>]

On 11/21/23 2:09 PM, John Baldwin wrote:
> If a target provides a target description including registers from the
> XSAVE extended region, but does not provide an XSAVE layout, use a
> fallback XSAVE layout based on the included registers.  This fallback
> layout matches GDB's behavior in earlier releases which assumes the
> layout from Intel CPUs.
> 
> This fallback layout is currently only used for remote targets since
> native targets which support XSAVE provide an explicit layout derived
> from CPUID.
> 
> PR gdb/30912
> Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30912

This fixes the regression for me locally.  It would perhaps be cleaner
to isolate the regression to the remote target by moving the new logic
in i386_gdbarch_init into remote::fetch_x86_xsave_layout.  The one
caveat of that is getting access to the right tdesc.  I could perhaps
change target::fetch_x86_xsave_layout to pass down the tdesc pointer
(or maybe the gdbarch_info?).  Alternatively it might be sufficient to
just use target_current_description() as the tdesc in remote.c?  It
wasn't clear to me if the relevant tdesc in this case was always the
same as target_current_description() (though I suspect it probably is).

-- 
John Baldwin