From: Pedro Alves <palves@redhat.com>
To: Ulrich Weigand <uweigand@de.ibm.com>
Cc: Andreas Arnez <arnez@linux.vnet.ibm.com>, gdb-patches@sourceware.org
Subject: Re: [PATCH 0/6] S390: Watchpoint enhancements and hardware breakpoints
Date: Fri, 16 Sep 2016 15:43:00 -0000 [thread overview]
Message-ID: <c0d0de65-429d-7449-7f98-f8aefb1058e7@redhat.com> (raw)
In-Reply-To: <20160916124323.AE052FE999@oc8523832656.ibm.com>
On 09/16/2016 01:43 PM, Ulrich Weigand wrote:
> Pedro Alves wrote:
>> I'm curious on the need to disable hw breakpoints when single-stepping.
>
> This is more of a hardware restriction than a GDB issue. The problem is
> that s390 hardware doesn't really have a separate hardware single-step
> feature; to implement ptrace single-stepping, the kernel uses the s390
> hardware breakpoint feature (in effect, enabling hardware breakpoints
> on the full address space, which will hit on the next instruction that
> is executed).
>
> This use of the feature by kernel single-stepping can conflict with
> explicit use of the same feature by GDB; that's why it is better to
> not attempt such explicit use while at the same time also requesting
> kernel single-stepping.
I see. Thanks for the clarification.
A comment to the effect in the code would be nice. Maybe it's
there and I missed it.
I have no further comments on the series. LGTM.
Thanks,
Pedro Alves
next prev parent reply other threads:[~2016-09-16 15:43 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-15 11:53 Andreas Arnez
2016-09-15 11:54 ` [PATCH] Fix order of inferiors in "thread apply all" Andreas Arnez
2016-09-15 12:03 ` Andreas Arnez
2016-09-15 11:59 ` [PATCH 1/6] S390: Avoid direct access to lwp_info structure Andreas Arnez
2016-09-15 12:01 ` [PATCH 3/6] S390: Multi-inferior watchpoint support Andreas Arnez
2016-09-15 12:02 ` [PATCH 6/6] S390: Hardware breakpoint support Andreas Arnez
2016-09-15 12:02 ` [PATCH 2/6] S390: Migrate watch areas from list to VEC type Andreas Arnez
2016-09-15 12:02 ` [PATCH 4/6] S390: Enable "maint set show-debug-regs" Andreas Arnez
2016-09-15 12:02 ` [PATCH 5/6] linux-nat: Add function lwp_is_stepping Andreas Arnez
2016-09-15 15:08 ` Yao Qi
2016-09-15 14:11 ` [PATCH 0/6] S390: Watchpoint enhancements and hardware breakpoints Pedro Alves
2016-09-16 12:43 ` Ulrich Weigand
2016-09-16 15:43 ` Pedro Alves [this message]
2016-09-16 17:30 ` Andreas Arnez
2016-09-15 14:58 ` Yao Qi
2016-09-15 17:14 ` Andreas Arnez
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