Re: Need for KEXEC_PRESERVE_CONTEXT flag ?

From: Neil Horman <nhorman@redhat.com>
To: Indraneel Mukherjee <indro.ml@gmail.com>
Cc: kexec@lists.infradead.org
Subject: Re: Need for KEXEC_PRESERVE_CONTEXT flag ?
Date: Sun, 21 Jun 2009 13:17:09 -0400	[thread overview]
Message-ID: <20090621171709.GA3358@localhost.localdomain> (raw)
In-Reply-To: <48e37220906182330w6a6e83bctb3b3a27f7bfc6afb@mail.gmail.com>

On Fri, Jun 19, 2009 at 12:00:44PM +0530, Indraneel Mukherjee wrote:
> Hi,
> 
> The file kernel/kexec.c (~ line 1001 in linux-2.6.30) has this code
> 
> ------snip----
> 
>  if (flags & KEXEC_PRESERVE_CONTEXT)
>             image->preserve_context = 1;
> 
> ------snip----
> 
> Will this ever be true? The flag KEXEC_PRESERVE_CONTEXT is not even defined
> in kexec-tools-2.0.0.
> 
> Consequently, all the code inside the condition  if(image->preserve_context)
>   is also useless?
> 
> Am i missing something here?
> 
Yes, the code you're looking at in the first definition is part of the kernel,
while you're looking for the definition of KEXEC_PRESERVE_CONTEXT in the
kexec-tools userspace code.  You need to look for the definition of
KEXEC_PRESERVE_CONTEXT in the kernel code (you'll find it in
include/linux/kexec.h).  kexec-tools might use it one day, but not using it
doesn't mean we should remove it from the kernel.

Neil

> Regards,
> Indro

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