Re: [PATCH v2 00/12] treewide: break dependencies on x86's RM header

Ingo Molnar
2019-11-27T07:20:57Z

* Sean Christopherson <sean.j.christopherson@intel.com> wrote:

> x86's asm/realmode.h, which defines low level structures, variables and
> helpers used to bring up APs during SMP boot, ends up getting included in
> practically every nook and cranny of the kernel because the address used
> by ACPI for resuming from S3 also happens to be stored in the real mode
> header, and ACPI bleeds the dependency into its widely included headers.
>
> As a result, modifying realmode.h for even the most trivial change to the
> boot code triggers a full kernel rebuild, which is frustrating to say the
> least as it some of the most difficult code to get exactly right *and* is
> also some of the most functionally isolated code in the kernel.
>
> To break the kernel's widespread dependency on realmode.h, add a wrapper
> in the aforementioned ACPI S3 code to access the real mode header instead
> of derefencing the header directly in asm/acpi.h and thereby exposing it
> to the world via linux/acpi.h.
>
> v2:
> - Rebased on tip/x86/cleanups, commit b74374fef924 ("x86/setup: Enhance
> the comments").
> - Use acpi_get_wakeup_address() as new function name. [Boris and Pavel]
> - Capture acpi_get_wakeup_address() in a local address. [Pavel]
> - Collect acks. I didn't add Rafael's acks on patches 11 and 12 due to
> the above changes.
> - Explicitly call out the removal of <asm/realmode.h> from <asm/acpi.h>
> in patch 12. [Ingo]
> - Remove superfluous Fixes: tags. [Ard]

You didn't include every patch from v1 though, such us my fix to Quark:

[PATCH] x86/platform/intel/quark: Explicitly include linux/io.h for virt_to_phys()

I've applied that one too and your updated patches, and it's now all
pushed out into tip:WIP.core/headers.

Thanks,

Ingo