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From: Vivek Goyal <vgoyal@redhat.com>
To: Prarit Bhargava <prarit@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>, Jonathan Corbet <corbet@lwn.net>,
	kexec@lists.infradead.org, Rusty Russell <rusty@rustcorp.com.au>,
	linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
	Fabian Frederick <fabf@skynet.be>,
	isimatu.yasuaki@jp.fujitsu.com, "H. Peter Anvin" <hpa@zytor.com>,
	Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-api@vger.kernel.org, jason.wessel@windriver.com
Subject: Re: [PATCH V4] kernel, add bug_on_warn
Date: Tue, 28 Oct 2014 08:29:00 -0400	[thread overview]
Message-ID: <20141028122900.GA10632@redhat.com> (raw)
In-Reply-To: <544F8A78.9070008@redhat.com>

On Tue, Oct 28, 2014 at 08:22:16AM -0400, Prarit Bhargava wrote:
> 
> 
> On 10/28/2014 08:16 AM, Andi Kleen wrote:
> > On Fri, Oct 24, 2014 at 08:53:27AM -0400, Prarit Bhargava wrote:
> >> There have been several times where I have had to rebuild a kernel to
> >> cause a panic when hitting a WARN() in the code in order to get a crash
> >> dump from a system.  Sometimes this is easy to do, other times (such as
> >> in the case of a remote admin) it is not trivial to send new images to the
> >> user.
> >>
> >> A much easier method would be a switch to change the WARN() over to a
> >> BUG().  This makes debugging easier in that I can now test the actual
> >> image the WARN() was seen on and I do not have to engage in remote
> >> debugging.
> > 
> > IMHO this would be better and far more generically done with kdb. 
> > You would need two things:
> > 
> > - Extend the break point command to run another command on a break point.
> > - Add a command line (or possibly /proc) option to execute some kdb commands at
> > kernel boot.
> 
> 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.

Thanks
Vivek

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WARNING: multiple messages have this Message-ID (diff)
From: Vivek Goyal <vgoyal@redhat.com>
To: Prarit Bhargava <prarit@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>,
	linux-kernel@vger.kernel.org, Jonathan Corbet <corbet@lwn.net>,
	Andrew Morton <akpm@linux-foundation.org>,
	Rusty Russell <rusty@rustcorp.com.au>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
	Fabian Frederick <fabf@skynet.be>,
	isimatu.yasuaki@jp.fujitsu.com, linux-doc@vger.kernel.org,
	kexec@lists.infradead.org, linux-api@vger.kernel.org,
	jason.wessel@windriver.com
Subject: Re: [PATCH V4] kernel, add bug_on_warn
Date: Tue, 28 Oct 2014 08:29:00 -0400	[thread overview]
Message-ID: <20141028122900.GA10632@redhat.com> (raw)
In-Reply-To: <544F8A78.9070008@redhat.com>

On Tue, Oct 28, 2014 at 08:22:16AM -0400, Prarit Bhargava wrote:
> 
> 
> On 10/28/2014 08:16 AM, Andi Kleen wrote:
> > On Fri, Oct 24, 2014 at 08:53:27AM -0400, Prarit Bhargava wrote:
> >> There have been several times where I have had to rebuild a kernel to
> >> cause a panic when hitting a WARN() in the code in order to get a crash
> >> dump from a system.  Sometimes this is easy to do, other times (such as
> >> in the case of a remote admin) it is not trivial to send new images to the
> >> user.
> >>
> >> A much easier method would be a switch to change the WARN() over to a
> >> BUG().  This makes debugging easier in that I can now test the actual
> >> image the WARN() was seen on and I do not have to engage in remote
> >> debugging.
> > 
> > IMHO this would be better and far more generically done with kdb. 
> > You would need two things:
> > 
> > - Extend the break point command to run another command on a break point.
> > - Add a command line (or possibly /proc) option to execute some kdb commands at
> > kernel boot.
> 
> 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.

Thanks
Vivek

  reply	other threads:[~2014-10-28 12:29 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-10-24 12:53 [PATCH V4] kernel, add bug_on_warn Prarit Bhargava
2014-10-24 12:53 ` Prarit Bhargava
2014-10-27 18:05 ` Jason Baron
2014-10-27 18:05   ` Jason Baron
2014-10-27 18:05   ` Jason Baron
2014-10-27 18:15   ` Prarit Bhargava
2014-10-27 18:15     ` Prarit Bhargava
2014-10-27 18:15     ` Prarit Bhargava
2014-10-28  2:32     ` Dave Young
2014-10-28  2:32       ` Dave Young
2014-10-28  5:41     ` Masami Hiramatsu
2014-10-28  5:41       ` Masami Hiramatsu
2014-10-28  0:00 ` Yasuaki Ishimatsu
2014-10-28  0:00   ` Yasuaki Ishimatsu
2014-10-28  0:00   ` Yasuaki Ishimatsu
2014-10-28 12:16 ` Andi Kleen
2014-10-28 12:16   ` Andi Kleen
2014-10-28 12:22   ` Prarit Bhargava
2014-10-28 12:22     ` Prarit Bhargava
2014-10-28 12:22     ` Prarit Bhargava
2014-10-28 12:29     ` Vivek Goyal [this message]
2014-10-28 12:29       ` Vivek Goyal
2014-10-28 12:44       ` Andi Kleen
2014-10-28 12:44         ` Andi Kleen
2014-10-28 12:48         ` Prarit Bhargava
2014-10-28 12:48           ` Prarit Bhargava
2014-10-28 12:48           ` Prarit Bhargava
2014-10-28 12:56           ` Andi Kleen
2014-10-28 12:56             ` Andi Kleen
2014-10-28 12:56             ` Andi Kleen
2014-10-28 13:19             ` Prarit Bhargava
2014-10-28 13:19               ` Prarit Bhargava
2014-10-28 13:19               ` Prarit Bhargava
2014-10-28 12:55         ` Vivek Goyal
2014-10-28 12:55           ` Vivek Goyal
2014-10-28 12:59           ` Andi Kleen
2014-10-28 12:59             ` Andi Kleen

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