linux-kernel - Re: [PATCH V4] kernel, add bug_on

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Message-ID: <544F90B1.1070102@redhat.com>
Date:	Tue, 28 Oct 2014 08:48:49 -0400
From:	Prarit Bhargava <prarit@...hat.com>
To:	Andi Kleen <ak@...ux.intel.com>
CC:	Vivek Goyal <vgoyal@...hat.com>, linux-kernel@...r.kernel.org,
	Jonathan Corbet <corbet@....net>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Rusty Russell <rusty@...tcorp.com.au>,
	"H. Peter Anvin" <hpa@...or.com>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Fabian Frederick <fabf@...net.be>,
	isimatu.yasuaki@...fujitsu.com, linux-doc@...r.kernel.org,
	kexec@...ts.infradead.org, linux-api@...r.kernel.org,
	jason.wessel@...driver.com
Subject: Re: [PATCH V4] kernel, add bug_on_warn



On 10/28/2014 08:44 AM, Andi Kleen wrote:
>>> I suppose ... but that would mean I would have to explain to an end user the
>>> elaborate process of enabling kdb, inserting a break point, etc.  The whole
>>> purpose of this is to let an end user panic on WARN() easily.
>>>
>>> Asking an end user to enable kdb is magnitudes worse than asking them to
>>> recompile a kernel.
>>
>> Agreed. Asking a customer to setup and run kdb and put breakpoints is much
>> more pain than simply asking to reboot kernel with a command line option.
> 
> If you have a command line option to execute kdb commands you still
> would only have a command line option, just a slightly longer one.
> 
> kdb="on, bp warn_slowpath_common sr c, go" 

KDB is not on all kernels.  This would require me to go to great lengths to
explain to a user how to set it up, etc., rather than saying "Hi, please add
panic_on_warn as a kernel parameter/echo 1 into /proc/sys/kernel/panic_on_warn
and on the next time you see that WARN() the system will panic and kdump.  Send
me that kdump."

> 
> But it would be a generic facility instead of a special purpose hack.

Generic to KDB be configured on and it is in no way trivial to use.

P.
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