Re: [PATCH] xen: do not reserve 2 pages of padding betweenhypervisor and fixmap.

[Ingo Molnar]

* Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:

> 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.
> 
> Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> Cc: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
> Cc: Signed-off-by: Ingo Molnar <mingo@xxxxxxx>

applied to tip/x86/xen, thanks Ian!

	Ingo
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