linux-kernel - Re: [PATCH] disable kaslr in kdump kernel

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Message-ID: <20140212140516.GA16470@redhat.com>
Date:	Wed, 12 Feb 2014 09:05:16 -0500
From:	Vivek Goyal <vgoyal@...hat.com>
To:	Dave Young <dyoung@...hat.com>
Cc:	keescook@...omium.org, hpa@...or.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] disable kaslr in kdump kernel

On Wed, Feb 12, 2014 at 09:37:34AM +0800, Dave Young wrote:
> On 02/11/14 at 08:16am, Vivek Goyal wrote:
> > On Tue, Feb 11, 2014 at 06:08:38PM +0800, Dave Young wrote:
> > > 
> > > KASLR does not work in kdump kernel because it's too early that mem=exactmap
> > > has not been parsed.
> > > 
> > > Since KASLR does not make much sense for kdump kernel thus let's disable it
> > > for kdump kernel. To check if it is a kdump kernel I just check the cmdline
> > > param elfcorehdr just like is_kdump_kernel.
> > > 
> > > Signed-off-by: Dave Young <dyoung@...hat.com>
> > 
> > I don't think it is a good idea. I don't like hardcoding second kernel's
> > behavior. I rather vary second kernel's behavior based on command line
> > parameters or based on values passed in bootparams.
> > 
> > So I am more than happy to pass command line option "nokaslr" instead
> > of hardcoding this in kernel.
> 
> That's also fine to me, but I think we'd better add it to documentation?

Adding documentation is fine. May be Documentation/kdump/kdump.txt. Create
a section where we mention some of the preferred command line settings
for kdump to work.

Thanks
Vivek
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