linux-kernel - Re: [patch 1/3] kdump: use is_kdump_kernel() in sba

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Message-ID: <20080729224039.GE6370@verge.net.au>
Date:	Wed, 30 Jul 2008 08:40:41 +1000
From:	Simon Horman <horms@...ge.net.au>
To:	Vivek Goyal <vgoyal@...hat.com>
Cc:	kexec@...ts.infradead.org, linux-ia64@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [patch 1/3] kdump: use is_kdump_kernel() in sba_init()

On Tue, Jul 29, 2008 at 10:51:56AM -0400, Vivek Goyal wrote:
> On Tue, Jul 29, 2008 at 06:12:36PM +1000, Simon Horman wrote:
> > After recent patches* is_kdump_kernel() should return 1 in the
> > case where code is executing in a crashkernel and 0 otherwise.
> > It is save to use outside of CONFIG_KDUMP.
> > 
> > * http://lkml.org/lkml/2008/7/28/445
> > 
> 
> Hi Simon,
> 
> is_kdump_kernel() returns 1 when both the following conditions are true.
> 
> - CONFIG_CRASH_DUMP is enabled
> - And kernel is booting after a panic.
> 
> If any of the above condition is not true, it returns 0.
> 
> So for the cases where, CONFIG_CRASH_DUMP=n and kernel is booting after
> panic, is_kdump_kernel() will still return 0.
> 
> This essentially means that any kernel which is booting after a panic,
> but does not have CONFIG_CRASH_DUMP enabled, will not take special actions
> required for booting that kernel. Until, somebody can come up with another
> usage of booting a kernel after a panic (apart from crash dump), I think
> this is good enough an assumption.
> 
> So your changes will work. I just wanted to clarify the semantics more
> explicitly.

Hi Vivek,

sorry if my explanation was confused. The scheme that you describe
above is what I am working with too.

-- 
Horms

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