linux-kernel - Re: [PATCH 06/11] x86/xen: Add i386 kexec/kdump implementation

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Date:	Fri, 28 Sep 2012 09:11:47 +0100
From:	"Jan Beulich" <JBeulich@...e.com>
To:	"Daniel Kiper" <daniel.kiper@...cle.com>
Cc:	<andrew.cooper3@...rix.com>, "xen-devel" <xen-devel@...ts.xen.org>,
	<konrad.wilk@...cle.com>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 06/11] x86/xen: Add i386 kexec/kdump implementation

>>> On 27.09.12 at 20:06, Daniel Kiper <daniel.kiper@...cle.com> wrote:
> Add i386 kexec/kdump implementation.

So this as well as the subsequent patch introduces quite a bit of
duplicate code. The old 2.6.18 kernel had an initial pair of cleanup
patches (attached in their forward ported form for 3.6-rc6) that
would allow reducing the amount of duplication, particularly by
eliminating the need to clone relocate_kernel_??.S altogether.

Additionally, in the PAE case (which is the only relevant one for
a 32-bit Xen kernel) I'm missing the address restriction
enforcement for the PGD, without which the __ma() conversion
result may not fit into the field it gets stored into.

Finally, as noticed in an earlier patch already, you appear to
re-introduce stuff long dropped from the kernel - the forward
ported kernels get away with just setting PA_CONTROL_PAGE,
PA_PGD, and PA_SWAP_PAGE in the page list. Since the number
and purpose of the pages is established entirely by the guest
kernel, all you need to obey is that the hypervisor expects
alternating PA_/VA_ pairs (where the VA_ ones can be left
unpopulated). Perhaps taking a look at a recent SLES kernel
would help...

Jan

View attachment "kexec-move-segment-code-x86_64.patch" of type "text/plain" (4215 bytes)

View attachment "kexec-move-segment-code-i386.patch" of type "text/plain" (4400 bytes)