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Re: [Xen-devel] REGRESSION: Xen 4.13 RC5 fails to bootstrap Dom0 on ARM

Hi Roman,

On 18/12/2019 17:03, Roman Shaposhnik wrote:
On Wed, Dec 18, 2019 at 3:50 AM Julien Grall <julien@xxxxxxx> wrote:
So -- nothing boots directly by UEFI -- everything goes through GRUB.

However, my understanding is that GRUB will detect devicetree
information provided by UEFI (even though devicetree command is
supposed to completely replace that). Hence it is possible that Linux
relies on some residuals left in memory by GRUB that Xen doesn't pay
attention to (but this is a pretty wild speculation only).

While it goes through GRUB, it is a bootloader and will just act as a proxy for EFI. So EFI application such as Xen/Linux can still be loaded and take advantage of runtime servies if present/implemented.

In fact most of people on Arm are using GRUB rather than EFI directly as this is more friendly to use.

Regarding the devicetree, Xen and Linux will completely ignore the memory nodes in Xen if using EFI. This because the EFI memory map will give you an overview of the platform with the EFI regions included.


Julien Grall

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