Re: [PATCH] Kwatch: kernel watchpoints using CPU debug registers

From: S. P. Prasanna
Date: Thu Feb 22 2007 - 06:43:05 EST

On Wed, Feb 21, 2007 at 03:35:13PM -0500, Alan Stern wrote:
> Going back to something you mentioned earlier...
> On Fri, 9 Feb 2007, Roland McGrath wrote:
> There are two things I am uncertain about: vm86 mode and kprobes. I don't
> know anything about how either of them works. Judging from the current
> code, nothing much should be needed -- debug traps in vm86 mode are
> handled by calling handle_vm86_trap(), and kprobes puts itself at the
> start of the notify_die() chain so it can handle single-step traps.
> Eventually it will be necessary to check with someone who really
> understands the issues.

Yes, Kprobes needs to get notified first to handle single-step traps. So kwatch
getting notified secound should be fine.

Prasanna S.P.
Linux Technology Center
India Software Labs, IBM Bangalore
Email: prasanna@xxxxxxxxxx
Ph: 91-80-41776329
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