RFC: ARM: Support for VFP/NEON registers in coredumps
Ulrich.Weigand at de.ibm.com
Thu Mar 24 18:11:16 UTC 2011
Dave Martin <dave.martin at linaro.org> wrote:
> On Thu, Mar 24, 2011 at 4:40 PM, Ulrich Weigand
<Ulrich.Weigand at de.ibm.com> wrote:
> > I would prefer to keep the contents of NT_VFPREGSET identical to the
> > contents of the PTRACE_GETVPFREGS/PTRACE_SETVPFREGS buffer:
> > - This would allow implementation via the new generic user_regset_view
> > mechanism (which the ARM kernel doesn't use yet, but probably should)
> > - In any case, GDB likes to have the same set of information available
> > when debugging core files and native targets
> > So if there is indeed additional information that would be interesting,
> > I'd argue this should be presented as a *new* core file note, *and* as
> > a new set of PTRACE_... APIs. (But for GDB's purpose NT_AUXV right
> > now is sufficent. Everything else could be displayed to the user if
> > of interest.)
> OK, that sounds reasonable.
> If I'm reading the kernel code correctly, the size of the data
> returned by PTRACE_GETVFPREGS is already dependent on the number of
> registers (D16/D32) implemented by the hardware, and this is
> determinable from the auxv contents; so I guess we don't have a new
> problem to solve here.
> The other info can always be added in a later pass, if it looks like
> it would be useful...
So to summarize: the kernel will write additional note sections as if
generated via user_regset_view, containing the PTRACE_GETVFPREGS data.
Note name: "LINUX"
Note type: t.b.d. [*]
[*] Looking at elf.h a logical name/value might be:
#define NT_ARM_VFP 0x400 /* ARM VFP/NEON registers */
GDB support along those lines ought to be straightforward.
Mit freundlichen Gruessen / Best Regards
Dr. Ulrich Weigand | Phone: +49-7031/16-3727
STSM, GNU compiler and toolchain for Linux on System z and Cell/B.E.
IBM Deutschland Research & Development GmbH
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