linux-kernel - Re: [PATCH v3 00/11] xen: Initial kexec/kdump implementation

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Date:	Wed, 26 Dec 2012 20:02:30 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Daniel Kiper <daniel.kiper@...cle.com>
CC:	andrew.cooper3@...rix.com, ebiederm@...ssion.com,
	jbeulich@...e.com, konrad.wilk@...cle.com, maxim.uvarov@...cle.com,
	mingo@...hat.com, tglx@...utronix.de, vgoyal@...hat.com,
	x86@...nel.org, kexec@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	virtualization@...ts.linux-foundation.org,
	xen-devel@...ts.xensource.com
Subject: Re: [PATCH v3 00/11] xen: Initial kexec/kdump implementation

On 12/26/2012 06:18 PM, Daniel Kiper wrote:
> Hi,
>
> This set of patches contains initial kexec/kdump implementation for Xen v3.
> Currently only dom0 is supported, however, almost all infrustructure
> required for domU support is ready.
>
> Jan Beulich suggested to merge Xen x86 assembler code with baremetal x86 code.
> This could simplify and reduce a bit size of kernel code. However, this solution
> requires some changes in baremetal x86 code. First of all code which establishes
> transition page table should be moved back from machine_kexec_$(BITS).c to
> relocate_kernel_$(BITS).S. Another important thing which should be changed in that
> case is format of page_list array. Xen kexec hypercall requires to alternate physical
> addresses with virtual ones. These and other required stuff have not been done in that
> version because I am not sure that solution will be accepted by kexec/kdump maintainers.
> I hope that this email spark discussion about that topic.
>

I want a detailed list of the constraints that this assumes and 
therefore imposes on the native implementation as a result of this.  We 
have had way too many patches where Xen PV hacks effectively nailgun 
arbitrary, and sometimes poor, design decisions in place and now we 
can't fix them.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

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