Re: [PATCH RESEND] ACPI/Kconfig: Make ACPI_NFIT depend on EFI_STUB on X86

From	Dan Williams <dan.j.williams@intel.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH RESEND] ACPI/Kconfig: Make ACPI_NFIT depend on EFI_STUB on X86
Date	2015-12-15 18:30 +0100
Message-ID	<qG1Ad-7eq-1@gated-at.bofh.it> (permalink)
References	<qG17c-6Oe-29@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Tue, Dec 15, 2015 at 8:59 AM, Toshi Kani <toshi.kani@hpe.com> wrote:
> ACPI 6.0 defines NFIT table and new persistent memory types for
> EFI memory table (EFI_PERSISTENT_MEMORY) and e820 table (E820_PMEM).
>
> setup_e820() enabled by EFI_STUB converts EFI_PERSISTENT_MEMORY to
> E820_PMEM for the e820_map table on x86 EFI platforms.  When EFI_STUB
> is disabled, x86 kernels rely on the bootloader to perform this
> conversion.
>
> It was found that the upstream grub bootloader since 2012 has a bug
> that converts EFI_PERSISTENT_MEMORY (or any new type) to E820_RAM,
> which causes the kernel to use persistent memory ranges as regular
> memory and corrupts the data in NVDIMM.
>
> Therefore, this patch sets ACPI_NFIT to depend on EFI_STUB on x86.
> This assures that ACPI_NFIT kernels are self-contained and are
> protected from the upstream grub bug on x86.
>
> Note, X86_PMEM_LEGACY allows the kernel to use the pmem driver on
> pre-ACPI 6.0 platforms, and does not require ACPI_NFIT enabled.
>
> References: http://www.mail-archive.com/grub-devel@gnu.org/msg23961.html
> Reported-by: Robert Elliott <elliott@hpe.com>
> Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
> Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
> Cc: Dan Williams <dan.j.williams@intel.com>
> ---
>  drivers/acpi/Kconfig |    1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
> index 5eef4cb..5368baa 100644
> --- a/drivers/acpi/Kconfig
> +++ b/drivers/acpi/Kconfig
> @@ -441,6 +441,7 @@ config ACPI_NFIT
>         depends on PHYS_ADDR_T_64BIT
>         depends on BLK_DEV
>         depends on ARCH_HAS_MMIO_FLUSH
> +       depends on !X86 || (X86 && EFI_STUB)
>         select LIBNVDIMM
>         help
>           Infrastructure to probe ACPI 6 compliant platforms for

This seems wrong to me.

In general Kconfig "depends on" are only about compile-time code
dependency, not about working around random bugs in external projects.
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Thread

[PATCH RESEND] ACPI/Kconfig: Make ACPI_NFIT depend on EFI_STUB on X86 Toshi Kani <toshi.kani@hpe.com> - 2015-12-15 18:00 +0100
  Re: [PATCH RESEND] ACPI/Kconfig: Make ACPI_NFIT depend on EFI_STUB on X86 Dan Williams <dan.j.williams@intel.com> - 2015-12-15 18:30 +0100
    Re: [PATCH RESEND] ACPI/Kconfig: Make ACPI_NFIT depend on EFI_STUB  on X86 Toshi Kani <toshi.kani@hpe.com> - 2015-12-15 19:00 +0100
      Re: [PATCH RESEND] ACPI/Kconfig: Make ACPI_NFIT depend on EFI_STUB  on X86 Toshi Kani <toshi.kani@hpe.com> - 2015-12-15 19:00 +0100
        Re: [PATCH RESEND] ACPI/Kconfig: Make ACPI_NFIT depend on EFI_STUB on X86 Dan Williams <dan.j.williams@intel.com> - 2015-12-15 19:10 +0100
          Re: [PATCH RESEND] ACPI/Kconfig: Make ACPI_NFIT depend on EFI_STUB  on X86 Toshi Kani <toshi.kani@hpe.com> - 2015-12-15 21:10 +0100
      Re: [PATCH RESEND] ACPI/Kconfig: Make ACPI_NFIT depend on EFI_STUB on X86 Dan Williams <dan.j.williams@intel.com> - 2015-12-15 19:00 +0100

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