Re: [Xen-devel] [PATCH 2 of 3] Enable UEFI BIOS(OVMF) support in Xen-unstable HVM

[Keir Fraser <keir.xen@xxxxxxxxx>]

On 09/08/2011 21:25, "Andrei Warkentin" <andreiw@xxxxxxxxxxxx> wrote:

>> I suspect ovmf-x64 is a superset of the capabilities of ovmf-ia32 (e.g.,
>> ability to boot UEFI-bootable 64-bit OSes?). If so, we should only support
>> one config option -- "ovmf" -- and have hvmloader auto-load the appropriate
>> OVMF build, based on CPUID.long_mode.
>> 
> 
> As Jordan mentioned, 32-bit EFI can only boot 32-bit EFI applications
> (that might mean 32-bit bootloader for 64-bit OS). 64-bit EFI can only
> boot 64-bit applications.

Good grief. How is that handled on real systems then: Are there two firmware
payloads? Or you can only boot 32-bit OS the legacy way on 64-bit server
systems?

> X64 is what is the "de facto" standard in the commerical PC/server
> world (for example - 2008, Win7 all boot UEFI way only on 64-bit), but
> 32-bit UEFI has been used as well and has applications in the
> low-power embedded x86 space.

I think we'll just stick with the two config options then -- ovmf-ia32 and
ovmf-x64. The correct choice depends on the OS that's installed, we can't
really auto-detect it, or if we do have that knowledge it will be from
within a higher-level management tool which can automatically set this
low-level config option appropriately.

 -- Keir



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