Date: Wed, 8 Feb 2012 23:20:19 +0400
From: Cyrill Gorcunov <gorcunov@openvz.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Pedro Alves <palves@redhat.com>, Pavel Emelyanov <xemul@parallels.com>,
        Jan Kratochvil <jan.kratochvil@redhat.com>, Tejun Heo <tj@kernel.org>,
        Andrew Vagin <avagin@openvz.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] ptrace: add ability to get clear_tid_address
Message-ID: <20120208192019.GM1909@moon>
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 <4F31945B.5000304@redhat.com>
 <20120207215121.GB29773@moon>
 <4F326AF7.3060203@redhat.com>
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On Wed, Feb 08, 2012 at 08:02:50PM +0100, Oleg Nesterov wrote:
> > Right, as I said.  :-)  I saw that a watchpoint trap isn't reported either
> > for the CLONE_CHILD_SETTID case (that is, within clone, when the kernel
> > writes the tid to the memory address passed in to the clone syscall).
> 
> Yes. But in this case the new thread has no bps even if it is auto-
> attached.
> 
> IOW, I think that hw bp can detect the write from the kernel space,
> but I didn't check.

yes, that's how kgdb work (if only I'm not missing something obvious)

	Cyrill
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