[RFA v2] (x86) Fix watchpoint using hardware breakpoint for some distro

[Xavier Roirand]

Hello Pedro,

Le 3/20/18 à 4:11 PM, Pedro Alves a écrit :
> On 03/20/2018 02:28 PM, Xavier Roirand wrote:
> Hmm, that's TRAP_BRKPT nowadays.  What was '1' supposed to mean in
> kernels of such vintage?  What was it's symbolic name back then?

As far as I can see in header file (/usr/include/bits/siginfo.h),
this is the same value, it's:

TRAP_BRKPT = 1,		/* Process breakpoint.  */

> In the table in linux-ptrace.h, we see that modern kernels report
> TRAP_BRKPT/1 for the "single-stepping a syscall" case.  What do
> those older kernels report in that case then?

When "single-stepping" syscall, the same value (TRAP_BRKPT) is
reported.

> What do those kernels report for hardware _breakpoints_?  Is it 1 too?

Yes, I've checked this and it's 1 also.

> Wondering whether we should make GDB_ARCH_IS_TRAP_HWBKPT return
> true for 1 too...
> 
> Please provide a more complete picture.
> 

Is it enough or do you think I need to provide more info ?

> Thanks,
> Pedro Alves
> 

Regards.