linux-kernel - Re: [patch v2 2/2] s390: Add architecture code for unmapping crashkernel memory

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Date:	Thu, 15 Sep 2011 10:48:03 +0200
From:	Michael Holzheu <holzheu@...ux.vnet.ibm.com>
To:	Vivek Goyal <vgoyal@...hat.com>
Cc:	Andrew Morton <akpm@...gle.com>, ebiederm@...ssion.com,
	mahesh@...ux.vnet.ibm.com, schwidefsky@...ibm.com,
	heiko.carstens@...ibm.com, kexec@...ts.infradead.org,
	linux-kernel@...r.kernel.org, linux-s390@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [patch v2 2/2] s390: Add architecture code for unmapping
 crashkernel memory

Hello Vivek, Andrew,

On Wed, 2011-09-14 at 14:29 -0400, Vivek Goyal wrote:
> On Wed, Sep 14, 2011 at 10:58:28AM +0200, Michael Holzheu wrote:
> > > Why not make this unconditional, for all architectures which support
> > > hugepages?  ie:
> > > 
> > > #ifdef HPAGE_SIZE
> > > #define KEXEC_CRASH_MEM_ALIGN HPAGE_SIZE
> > > #else
> > > #define KEXEC_CRASH_MEM_ALIGN PAGE_SIZE
> > > #endif
> > 
> > > in include/linux/kexec.h?
> > > 
> > > IOW, what are the compromises here?
> > 
> > If we would do it that way, crashkernel memory on architectures that
> > support large pages but do not support unmapping of crashkernel memory
> > would always be aligned to HPAGE_SIZE. But only PAGE_SIZE alignment
> > would be necessary in that case.
> > 
> > If that is acceptable I have no problem to define that unconditional for
> > all architectures. Vivek what do you think?
> 
> As PAGE_SIZE alignment is sufficient for rest of the architecture, I 
> am fine with keeping it in arch dependent files.

Ok fine. So I will resend the two patches including Andrew's
resource_size() fix and keep KEXEC_CRASH_MEM_ALIGN definition
architecture dependent.

Michael

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