Hi Grygorii,

On 06/08/2025 10:49, Grygorii Strashko wrote:
From: Grygorii Strashko <grygorii_stras...@epam.com>

Now Arm64 AArch32 guest support is always enabled and built-in while not
all Arm64 platforms supports AArch32 (for exmaple on Armv9A) or this

typo s/exmaple/example/

support might not be needed (Arm64 AArch32 is used quite rarely in embedded
systems).


> More over, when focusing on safety certification, AArch32 related> code in Xen leaves a gap in terms of coverage that cannot really be
justified in words. This leaves two options: either support it (lots of
additional testing, requirements and documents would be needed) or compile
it out.

To clarify my understanding, what you are removing is support for 32-bit EL1. But 32-bit EL0 will still be supported. Is that correct?

[...]

- do not expose EL1 AArch32 support to guest in ID_AA64PFR0_EL1 reg if
   AArch32 is disabled.

A guest is not allowed to switch bitness. So I am not sure why we need to hide EL1. Depending on the answer above, you might need to hide EL0 and have more code (TBC) to prevent 32-bit EL0 running.

Cheers,

--
Julien Grall


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