On Tue, 2015-12-15 at 10:05 -0800, Dan Williams wrote: > On Tue, Dec 15, 2015 at 9:56 AM, Toshi Kani <toshi.kani@xxxxxxx> wrote: > > On Tue, 2015-12-15 at 09:53 -0800, Dan Williams wrote: > [..] > > > > > > 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. > > > > > > > > I agree that they do not have a compile dependency, and it looks > > > > rather odd. On the other hand, proper support of the ACPI NFIT > > > > extensions has a functional dependency to setup_e820() as this is > > > > the only code that can handle the EFI_PERSISTENT_MEMORY type today. > > > > > > What about non-EFI/legeacy-boot systems that only emit e820-type-7? > > > We lose support for them with this patch, right? > > > > No, having EFI_STUB does not break the legacy BIOS boot. > > > > Sorry let me clarify. A kernel compiled without EFI_STUB loses NFIT > support. I think it is the other way around. When NFIT is needed, one will enable all dependent options. So, an NFIT kernel will have to have EFI code as a result, even though it runs on the legacy BIOS. I believe distributed kernels enable EFI already so that they run on both legacy and EFI platforms. Of course, one may wish to build a smallest kernel specific to NFIT & legacy BIOS platforms and want to disable EFI code, but that seems to be a special case to me. > Non-EFI and legacy-boot systems don't have this grub bug to > worry about, so the dependency is overly restrictive, "breaks", those > environments. Yes, we do not have the grub bug on legacy BIOS (although PMEM ranges will show up as Reserved in the iomem table). I do not think NFIT being dependent on EFI is overly restrictive, but I may be wrong and I agree to drop this patch if that is indeed the case. Thanks, -Toshi -- 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
