Re: Building 32-bit xen.efi for 32-bit EFI platforms

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 24/11/14 14:59, Zhuan Chen wrote:
> Hi,
>
> I am wondering whether it's possible to build 32-bit xen.efi for the
> 32-bit EFI platform? One way of building xen.efi I learnt is to make
> the binutils configured with the x86_64-pep emulation (according to
> the document http://xenbits.xenproject.org/docs/unstable/misc/efi.html).
> The resulted xen.efi is 64-bit mode. Is it possible to build xen.efi
> as the 32-bit mode?
>
> The reason for this question is due to my effort of installing Xen on
> the Asus Transformer Book T100, which is one of the Bay Trail Atom
> (64-bit processors) tablets shipped with 32-bit EFI firmware. This
> requires the support of the 32-bit EFI bootloader. Such platforms seem
> to become common and Linux kernel from 3.15 also provides the EFI
> mixed mode to support 64-bit kernels running from 32-bit EFI firmware.
>
> Thanks,
> Zhuan

32bit Xen support was removed in Xen 4.3, so building a pure 32bit
hypervisor is not possible.

There is an argument to be made for building a 32bit Xen.efi which is
bootable by a 32bit firmware and moves into 64bit mode on boot.

There is however no support for this that I am aware of.

~Andrew