linux-kernel - Re: [PATCH v4 4/4] pr_emerg add WARN

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Date:	Tue, 2 Feb 2016 15:18:39 -0700
From:	Jeffrey Merkey <jeffmerkey@...il.com>
To:	"Maciej W. Rozycki" <macro@...ux-mips.org>
Cc:	Steven Rostedt <rostedt@...dmis.org>, linux-kernel@...r.kernel.org,
	Jason@...c4.com, aconole@...hat.com,
	Andrew Morton <akpm@...ux-foundation.org>,
	andriy.shevchenko@...ux.intel.com, linus.walleij@...aro.org,
	nicolas.iooss_linux@....org, pmladek@...e.com, tj@...nel.org
Subject: Re: [PATCH v4 4/4] pr_emerg add WARN_XX() debugger options

On 2/2/16, Maciej W. Rozycki <macro@...ux-mips.org> wrote:
> On Mon, 1 Feb 2016, Jeffrey Merkey wrote:
>
>> If a debugger is loaded it will not crash, just enter the debugger.
>> But yes, it will int3 if set and no debugger has been loaded to handle
>> the int3 condition.  Hmmm.  Maybe its better just to skip calling
>> pr_emerg and put this logic as a single call somewhere else.
>
>  What's the point?  If you have a debugger loaded, then surely you can
> just set a breakpoint anywhere you like using whatever user interface the
> debugger provides for setting breakpoints.  You can actually set any
> number of software breakpoints you like wherever you like, depending on
> what you actually want to debug.  I fail to see why it would have to be
> prearranged within the kernel -- do you have a configuration where you run
> the kernel from ROM by any chance?
>
>   Maciej
>

No ROM here.  I resubmitted this as series 5 and dropped the change to
pr_emerg for the very reasons you stated.  I verified what you said
was correct by reviewing several code paths and its not a good place
for that.  Folks expect this function to act like a printk on
steroids, not as a terminal placement of a BUG().

Jeff