Re: [PATCH v2 0/4] Split hyperv-tlfs.h into generic and arch specific files

From: Wei Liu
Date: Thu Apr 23 2020 - 09:22:16 EST


On Wed, Apr 22, 2020 at 12:57:33PM -0700, Michael Kelley wrote:
> This series splits hyperv-tlfs.h into architecture independent and
> architecture specific files so that the arch independent portion can
> be shared between the x86/x64 and ARM64 code for Hyper-V. While the
> Hyper-V team has not released a version of the TLFS document that
> clearly specifies which portions of the interface are arch independent,
> we can make a fairly good assessment based on implementation work done
> to support Linux guests on Hyper-V on ARM64, and on private communication
> with the Hyper-V team. Definitions are considered arch independent if
> they are implemented by Hyper-V on both architectures (x86/x64 and ARM64),
> even if they are currently needed by Linux code only on one architecture.
>
> Many definitions in hyperv-tlfs.h have historically contained "X64" in the
> name, which doesn't make sense for architecture independent definitions.
> While many of the occurrences of "X64" have already been removed, some
> still remain in definitions that should be arch independent. The
> split removes the "X64" from the definitions so that the arch
> independent hyper-tlfs.h has no occurrences of "X64". However, to
> keep this patch set separate from a wider change in the names, aliases
> are added in the x86/x64 specific hyperv-tlfs.h so that existing code
> continues to compile. The definitions can be fixed throughout the code
> in a more incremental fashion in separate patches, and then the aliases
> can be removed.
>
> Where it is not clear if definitions are arch independent, they have been
> kept in the x86/x64 specific file. The Hyper-V team is aiming to have a
> version of the TLFS document covering ARM64 by the end of calendar 2020,
> so additional definitions may be moved into the arch independent portion
> after the new TLFS document is released.
>
> The first two patches in the series clean up the existing hyperv-tlfs.h
> file a bit by removing duplicate or unnecessary definitions so they are
> not propagated across the split. The third patch does the split, and the
> fourth patch adds new definitions that are needed on ARM64 but are generic.
>
> These changes have no functional impact.
>
> These patches are built against linux-next-20200415

Applied to hyperv-next. Thanks.

Wei.