Re: [Xen-devel] [PATCH 3/4] x86-64: EFI runtime code

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

>>> On 28.06.11 at 19:03, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> wrote:
> Ah, here it is: "acpi_os_get_root_pointer" uses the efi.acpi20 or
> efi.acpi and the DMI scan uses efi.smbios.
> 
> And those physical addresses reside within a reserved E820 region or
> a gap I hope.

That's how it's supposed to be. If we find systems where it lives
elsewhere, we'll have to add workarounds (in Xen).

>> Yes, it needs to, due to the table pointer retrieval differences. And
>> then there's the runtime services (RTC access, EFI variables) that
>> the OS ought to use. On the RTC side of things, a legacy free system
> 
> I am just looking at the minimal to understand it.
>> might not have a CMOS clock, and hence even native Linux is currently
>> broken in that respect (because the driver can be built only for IA64).
> 
> We do switch to the Xen clock (which is to say that the hypervisor is
> responsible for it) ... so I think we could skip the RTC in the Linux 
> kernel.

No, Dom0 has to manage the RTC (and so it does today, at least
in all non-pvops kernels I know of).

Jan


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