On Thu, Feb 25, 2021 at 07:29:07PM +0100, David Hildenbrand wrote:
> On 09.02.21 14:38, Oscar Salvador wrote:
> > Enable x86_64 platform to use the MHP_MEMMAP_ON_MEMORY feature.
> >
> > Signed-off-by: Oscar Salvador <osalvador@xxxxxxx>
> > ---
> > arch/x86/Kconfig | 4 ++++
> > 1 file changed, 4 insertions(+)
> >
> > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> > index 72663de8b04c..81046b7adb10 100644
> > --- a/arch/x86/Kconfig
> > +++ b/arch/x86/Kconfig
> > @@ -2440,6 +2440,10 @@ config ARCH_ENABLE_MEMORY_HOTREMOVE
> > def_bool y
> > depends on MEMORY_HOTPLUG
> > +config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
> > + def_bool y
> > + depends on X86_64 && MEMORY_HOTPLUG && SPARSEMEM_VMEMMAP_ENABLE
>
> It depends on SPARSEMEM_VMEMMAP, no?
>
> I think we could have
>
> SPARSEMEM_VMEMMAP_ENABLE=y
> and
> SPARSEMEM_VMEMMAP=n
>
> on manually tuned configs.
I do not think this can happen:
from mm/Kconfig:
config SPARSEMEM_VMEMMAP_ENABLE
bool
config SPARSEMEM_VMEMMAP
bool "Sparse Memory virtual memmap"
depends on SPARSEMEM && SPARSEMEM_VMEMMAP_ENABLE
default y
help
SPARSEMEM_VMEMMAP uses a virtually mapped memmap to optimise
pfn_to_page and page_to_pfn operations. This is the most
efficient option when sufficient kernel resources are available
and from arch/x86/Kconfig:
config ARCH_SPARSEMEM_ENABLE
def_bool y
depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
select SPARSEMEM_STATIC if X86_32
select SPARSEMEM_VMEMMAP_ENABLE if X86_64
So, if I read this correctly, for SPARSEMEM_VMEMMAP to be true,
SPARSEMEM_VMEMMAP_ENABLE needs to be true as well.
Am I missing something?
--
Oscar Salvador
SUSE L3
