linux-kernel - Re: [PATCH 01/31] Add hard/soft lockup debugger entry points

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Message-ID: <alpine.DEB.2.11.1601282052480.3886@nanos>
Date:	Thu, 28 Jan 2016 20:56:52 +0100 (CET)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Jeffrey Merkey <jeffmerkey@...il.com>
cc:	linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
	dzickus@...hat.com, uobergfe@...hat.com, atomlin@...hat.com,
	mhocko@...e.cz, fweisbec@...il.com, tj@...nel.org,
	hidehiro.kawai.ez@...achi.com, cmetcalf@...hip.com
Subject: Re: [PATCH 01/31] Add hard/soft lockup debugger entry points

On Thu, 28 Jan 2016, Jeffrey Merkey wrote:

> This patch series adds an export which can be set by system debuggers to
> direct the hard lockup and soft lockup detector to trigger a breakpoint
> exception and enter a debugger if one is active.  It is assumed that if
> someone sets this variable, then an breakpoint 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.

Why do we need an extra breakpoint instruction in the code to enter a
debugger? Don't have debuggers mechanisms to install breakpoints?

I'm probably missing something obvious here.

Thanks,

	tglx