Re: Change 5c371b31be3203 in stable breaks Xen

From: Ian Campbell
Date: Tue Nov 25 2008 - 18:06:26 EST


On Tue, 2008-11-25 at 13:26 -0800, Jeremy Fitzhardinge wrote:
> I have a report of Xen breaking between 2.6.27.5 and .6. I bisected
> it
> down to change:
>
> commit 5c371b31be32033b0a4a993431484da8a2305369
> Author: Yinghai Lu <yhlu.kernel@xxxxxxxxx>
> Date: Mon Sep 22 02:52:26 2008 -0700
>
> x86: fix CONFIG_X86_RESERVE_LOW_64K=y
>
> commit 2216d199b1430d1c0affb1498a9ebdbd9c0de439 upstream

Looks like 5dc64a3442b98eaa0e3730c35fcf00cf962a93e7 might be needed in
stable too?

commit 5dc64a3442b98eaa0e3730c35fcf00cf962a93e7
Author: Ian Campbell <Ian.Campbell@xxxxxxxxxx>
Date: Fri Oct 10 11:27:38 2008 +0100

xen: do not reserve 2 pages of padding between hypervisor and fixmap.

When reserving space for the hypervisor the Xen paravirt backend adds
an extra two pages (this was carried forward from the 2.6.18-xen tree
which had them "for safety"). Depending on various CONFIG options this
can cause the boot time fixmaps to span multiple PMDs which is not
supported and triggers a WARN in early_ioremap_init().

This was exposed by 2216d199b1430d1c0affb1498a9ebdbd9c0de439 which
moved the dmi table parsing earlier.
x86: fix CONFIG_X86_RESERVE_LOW_64K=y

The bad_bios_dmi_table() quirk never triggered because we do DMI setup
too late. Move it a bit earlier.

There is no real reason to reserve these two extra pages and the
fixmap already incorporates FIX_HOLE which serves the same
purpose. None of the other callers of reserve_top_address do this.


--
Ian Campbell

Moonchild without an opinion? Satan is skating to work tomorrow!
-- Brett Manz

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