linux-kernel - Re: [PATCH] kexec: use Crash kernel for Crash kernel low

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Message-ID: <20130401133428.GA13499@redhat.com>
Date:	Mon, 1 Apr 2013 09:34:28 -0400
From:	Vivek Goyal <vgoyal@...hat.com>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...e.hu>,
	WANG Chao <chaowang@...hat.com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	linux-kernel@...r.kernel.org, Yinghai Lu <yinghai@...nel.org>
Subject: Re: [PATCH] kexec: use Crash kernel for Crash kernel low

On Tue, Mar 26, 2013 at 02:14:18PM -0400, Vivek Goyal wrote:
> On Mon, Mar 25, 2013 at 02:50:18PM -0700, Yinghai Lu wrote:
> > On Mon, Mar 25, 2013 at 12:42 PM, Vivek Goyal <vgoyal@...hat.com> wrote:
> > > So it is a forgone conclusion that these new kernel changes to
> > > crashkernel=X in 3.9 are incompatible with older kexec-tools and one
> > > needs to upgrade kexec-tools.
> > 
> > I thought that you and hpa all agreed that user need to update kexec-tools with
> > new kernel v3.9. It that still right?
> 
> I can update kexec-tools and I don't have problems with that. I am only
> concerned about some xyz user complaining that new kernel stopped working
> with old kexec-tools and then possibly face the rant from Linus about
> breaking user space. :-)
> 
> To me we could maintain backward compatibility by retaining the existing
> behavior of crashkernle=X. That is  look for specificied memory below
> 896M first and then go higher.
> 
> And hide new semantics behind new kernel parameters or by extending
> existing parameter (say crashkernel=X:search_high_first) to specify how
> to search for reserved memory.
> 
> In both the cases we should probably retain the logic of auto reserving
> low memory for software iotlb and let user opt out if there is no need.
> 
> So we don't have a strong reason that why we should break existing
> kexec-tools. So I would prefer not to break it.
> 
> But I think this is hpa's decision.

hpa,

ping. Any thoughts on this?

Thanks
Vivek
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