On 26.02.21 13:04, Oscar Salvador wrote:
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 <[email protected]>
---
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?
Take your config and set
X86_5LEVEL=n
(because it enforces SPARSEMEM_VMEMMAP)
and
SPARSEMEM_VMEMMAP=n
When compiling, you'll end up with a config like
CONFIG_SPARSEMEM_VMEMMAP_ENABLE=y
# CONFIG_SPARSEMEM_VMEMMAP is not set
Yet, with your patch you would get
ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE=y
And it would not get fenced off in the code, right?
I think you either have to check (IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP))
in addition in your code, or enforce it differently. Like
config MHP_MEMMAP_ON_MEMORY
depends on SPARSEMEM_VMEMMAP && ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
bool
Then you can simplify the arch Kconfig settings, removing the sparesemem
dependency there.
--
Thanks,
David / dhildenb
