On Wed, Feb 20, 2019 at 11:21:45PM +0100, Rafael J. Wysocki wrote: > On Wed, Feb 20, 2019 at 11:11 PM Dave Hansen <dave.hansen@xxxxxxxxx> wrote: > > On 2/20/19 2:02 PM, Rafael J. Wysocki wrote: > > >> diff --git a/drivers/acpi/hmat/Kconfig b/drivers/acpi/hmat/Kconfig > > >> index c9637e2e7514..08e972ead159 100644 > > >> --- a/drivers/acpi/hmat/Kconfig > > >> +++ b/drivers/acpi/hmat/Kconfig > > >> @@ -2,6 +2,7 @@ > > >> config ACPI_HMAT > > >> bool "ACPI Heterogeneous Memory Attribute Table Support" > > >> depends on ACPI_NUMA > > >> + select HMEM_REPORTING > > > If you want to do this here, I'm not sure that defining HMEM_REPORTING > > > as a user-selectable option is a good idea. In particular, I don't > > > really think that setting ACPI_HMAT without it makes a lot of sense. > > > Apart from this, the patch looks reasonable to me. > > > > I guess the question is whether we would want to allow folks to consume > > the HMAT inside the kernel while not reporting it out via > > HMEM_REPORTING. We have some in-kernel users of the HMAT lined up like > > mitigations for memory-side caches. > > > > It's certainly possible that folks would want to consume those > > mitigations without anything in sysfs. They might not even want or need > > NUMA support itself, for instance. > > > > So, what should we do? > > > > config HMEM_REPORTING > > bool # no user-visible prompt > > default y if ACPI_HMAT > > > > So folks can override in their .config, but they don't see a prompt? > > Maybe it would be better to make HMEM_REPORTING do "select ACPI_HMAT if ACPI". > > The mitigations could then do that too if they depend on HMAT and > ACPI_HMAT need not be user-visible at all. That sounds okay, though it would create unreachable code if !ACPI since that's the only user for the new reporting interfaces.
