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Re: Regression for watchpoint-fork.exp [Re: [PATCH v3 2/5] PR breakpoints/7143 - Watchpoint does not trigger when first set]
- From: Pedro Alves <palves at redhat dot com>
- To: Jan Kratochvil <jan dot kratochvil at redhat dot com>
- Cc: Doug Evans <xdje42 at gmail dot com>, "gdb-patches at sourceware dot org" <gdb-patches at sourceware dot org>
- Date: Thu, 19 Jun 2014 16:02:00 +0100
- Subject: Re: Regression for watchpoint-fork.exp [Re: [PATCH v3 2/5] PR breakpoints/7143 - Watchpoint does not trigger when first set]
- Authentication-results: sourceware.org; auth=none
- References: <1394154640-14053-1-git-send-email-palves at redhat dot com> <1394154640-14053-3-git-send-email-palves at redhat dot com> <CAP9bCMTj+A2B6cvwYKC2vjL1Si+yGBKXvQfCMNR0SYN19KztXg at mail dot gmail dot com> <53272CB0 dot 6050101 at redhat dot com> <532AF3D0 dot 8090904 at redhat dot com> <20140617191850 dot GA10997 at host2 dot jankratochvil dot net> <20140619134330 dot GA14567 at host2 dot jankratochvil dot net>
On 06/19/2014 02:43 PM, Jan Kratochvil wrote:
> On Tue, 17 Jun 2014 21:18:50 +0200, Jan Kratochvil wrote:
>> On Thu, 20 Mar 2014 14:57:36 +0100, Pedro Alves wrote:
>>> Here's what I pushed (nothing else changed).
>>
>> 31e77af205cf6564c2bf4c18400b4ca16bdf92cd is the first bad commit
>> commit 31e77af205cf6564c2bf4c18400b4ca16bdf92cd
>> Author: Pedro Alves <palves@redhat.com>
>> Date: Thu Mar 20 13:26:32 2014 +0000
>> PR breakpoints/7143 - Watchpoint does not trigger when first set
>>
>> PASS kernel-3.14.6-200.fc20.x86_64
>> FAIL kernel-3.13.10-200.dentrybuflen.fc20.x86_64
>
> That was a red herring, in fact it was due to different GCC.
>
> (gdb) disas marker
> Dump of assembler code for function marker:
> 0x0000000000400826 <+0>: push %rbp
> 0x0000000000400827 <+1>: mov %rsp,%rbp
> => 0x000000000040082a <+4>: pop %rbp
> 0x000000000040082b <+5>: retq
> End of assembler dump.
>
> ptrace(PTRACE_POKEUSER, 24574, offsetof(struct user, u_debugreg), 0x40082a) = -1 EINVAL (Invalid argument)
>
> New GDB in the 'hbreak' case does not align the breakpoint address.
Hmm, I'm confused. Why would the breakpoint address need to be aligned?
And aligned to what?
> Attaching gzipped gdb.threads/watchpoint-fork-parent-st
> from gcc-4.9.0-9.fc21.x86_64.
Thanks, I can reproduce it.
--
Pedro Alves