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Re: [Xen-devel] Design doc of adding ACPI support for arm64 on Xen - version 3

On 17/08/2015 20:19, Shannon Zhao wrote:
Yes, I think it's good to drop the "linux," too. But if we drop the
linux, would it impact the linux kernel booting with UEFI? And why we
don't do it to Xen since Xen still uses "linux,"?

I don't understand your second question.

I mean that Xen is using the property "linux,uefi*" as well, and why we
don't drop that prefix for Xen?

As never say we shouldn't drop it in Xen... It's of course a nice clean up to have if we ever happen to standardize the properties with a different name.

For the first question, as we discussed in several mail, the property
"linux,uefi-*" are only used internally between the stub and Linux. The
sub is compiled in the kernel so there is no issue to change the property.

Since Linux defines the dt_params like below which is used to get EFI
info from DT, if we drop "linux," in Xen, does it need to drop the
"linux," in dt_params? If so, will this break the compatibility of
changed kernel with old UEFI? IIUC, there is not only Xen using these
properties, but also native host and QEMU guest.

I grepped "linux," and didn't spot any "linux,uefi-*" strings.

Anyway, why are you speaking about old UEFI? As said in different mail, the linux,uefi-* properties are only used internally between the EFI stub and the kernel. Both are living in the same binary so it's not exposed outside.

Those properties are not standardize so it would be wrong to use them to talk to the kernel.

Note that on Xen, we also used them internally. They were name "linux,uefi-*" because we re-use a part of the EFI stub from Linux. The names don't matter, so we can rename it without any issue


Julien Grall

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