linux-kernel - Re: [PATCH] Add hard/soft lockup debugger entry points

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Date:	Mon, 25 Jan 2016 21:47:38 -0500
From:	Chris Metcalf <cmetcalf@...hip.com>
To:	Jeff Merkey <linux.mdb@...il.com>, <linux-kernel@...r.kernel.org>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	Don Zickus <dzickus@...hat.com>,
	Ulrich Obergfell <uobergfe@...hat.com>,
	Aaron Tomlin <atomlin@...hat.com>,
	Michal Hocko <mhocko@...e.cz>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Tejun Heo <tj@...nel.org>,
	Hidehiro Kawai <hidehiro.kawai.ez@...achi.com>
Subject: Re: [PATCH] Add hard/soft lockup debugger entry points

On 1/25/2016 9:36 PM, Jeff Merkey wrote:
> This patch adds an export which can be set by system debuggers to direct
> the hard lockup and soft lockup detector to trigger an INT3 exception
> and enter a debugger if one is active.  It is assumed that if someone
> sets this variable, then an int3 handler of some sort will be actively
> loaded or registered via the notify die handler chain.
>
> This addition is extremely useful for debugging hard and soft lockups
> real time and quickly from a console debugger.
>
> Signed-off-by: Jeff Merkey<linux.mdb@...il.com>
> ---
>   kernel/watchdog.c | 9 +++++++++
>   1 file changed, 9 insertions(+)

Introducing Intel-specific assembly into generic code won't work. You would
need to add a framework to allow platforms to specify a debugging instruction
or maybe leverage some existing framework like arch_kgdb_breakpoint.

-- 
Chris Metcalf, EZChip Semiconductor
http://www.ezchip.com