Re: [PATCH 0/6] S390: Watchpoint enhancements and hardware breakpoints

[Pedro Alves <palves@redhat.com>]

On 09/15/2016 12:52 PM, Andreas Arnez wrote:
> This series adds some enhancements to the current s390-linux native
> support for watchpoints.  It also adds hardware breakpoint support.
> 
> While this is mostly an s390-specific series, it includes one
> common-code patch: patch #5, "linux-nat: Add function lwp_is_stepping".
> I'm looking for feedback on that.  Comments to the s390-specific patches
> are certainly welcome as well.

I'm curious on the need to disable hw breakpoints when single-stepping.

It's of course more efficient if we manage to disable the breakpoint just
for the thread that is stepping, without disturbing other threads, but
OTOH, infrun's handling of stepping over breakpoints should already be 
making sure that threads can step past breakpoints somehow?  I.e.,
without displaced stepping, infrun should be removing breakpoints from
all threads, and with displaced stepping, we'll be stepping the thread
at a different PC so the hardware breakpoint at the original PC should
not trigger.

Thanks,
Pedro Alves