On Tue, Dec 15, 2015 at 8:59 AM, Toshi Kani <toshi.kani@xxxxxxx> 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@xxxxxxx/msg23961.html > Reported-by: Robert Elliott <elliott@xxxxxxx> > Signed-off-by: Toshi Kani <toshi.kani@xxxxxxx> > Cc: Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> > Cc: Dan Williams <dan.j.williams@xxxxxxxxx> > --- > 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. -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
