Re: [Xen-devel] [PATCH for-4.10] libxc: load acpi RSDP table at correct address

[Juergen Gross <jgross@xxxxxxxx>]

On 20/11/17 10:51, Roger Pau Monné wrote:
> Adding xen-devel, dropped it on my reply. 
> 
>     Replying from my phone, sorry for the formatting. 
> 
> 
>     El 20 nov. 2017 9:35, "Juergen Gross" <jgross@xxxxxxxx
>     <mailto:jgross@xxxxxxxx>> escribió:
> 
>         For PVH domains loading of the ACPI RSDP table is done via
>         allocating
>         a domain loader segment after having loaded the kernel. This
>         leads to
>         the RSDP table being loaded at an arbitrary guest address instead of
>         the architectural correct address just below 1MB. 
> 
> 
>     AFAIK this is only true for legacy BIOS boot, when using UEFI the
>     RSDP can be anywhere in memory, hence grub2 must already have an
>     alternative way of finding the RSDP apart from scanning the low 1MB.

The problem isn't grub2, but the loaded linux kernel. Without this
patch Linux won't find the RSDP when booted in a PVH domain via grub2.

I could modify grub2 even further to move the RSDP to the correct
address, but I think doing it correctly on Xen side is the better
option.


Juergen

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