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Re: PATCH: gdbserver: Clear regcache if buf is NULL
On Saturday 16 October 2010 21:16:37, H.J. Lu wrote:
> >
> > Thanks, and sorry as for not coming back to this promptly.
> > Hmm, I don't think I have a way to trigger that.
> > So is the registers' value really zero, or should gdb
> > ideally present them as not available (and zero is just a
> > hack)?
> >
>
> You will see it only on machines with XSAVE and enabled in OS.
> Please see
>
> 13.6 XSAVE/XRSTOR AND PROCESSOR EXTENDED STATE
> MANAGEMENT
>
> in
>
> Intel® 64 and IA-32 Architectures Software Developer’s Manual
> Volume 3A: System Programming Guide, Part 1
>
> Basically values in vector registers may not be valid, depending
> on vector state.
Okay, thanks. The changes I'm working on would make gdb print
for such registers:
(gdb) info registers
...
foo-register *value not available*
...
rather than:
(gdb) info registers
...
foo-register 0x0 0
...
Trying to print the register's value will show something
like "$1 = <unavailable>", and using it's value in expression
evaluation to determine a computed expression value, an error
will be reported.
Does that sound good? Or do you think keep using 0 would
be better in this case?
--
Pedro Alves