On 05.02.2025 22:02, Shawn Anastasio wrote:
> Xen's memory management APIs map_pages_to_xen, modify_xen_mappings,
> set_fixmap, ioremap_attr, and __vmap all use an unsigned int to
> represent architecture-dependent page table entry flags. This assumption
> is not well-suited for PPC/radix where some flags go past 32-bits, so
> introduce the pte_attr_t type to allow architectures to opt in to larger
> types to store PTE flags.
> 
> Suggested-by: Andrew Cooper <[email protected]>
> Signed-off-by: Shawn Anastasio <[email protected]>
> ---
> Changes in v2:
>   - Drop Kconfig option and use `#define pte_attr_t pte_attr_t` for arches to
>   opt-in to defining the type.
>   - Move default pte_attr_definition to xen/types.h

I'm unconvinced of types.h being an appropriate place for something mm-
related. mm-types.h maybe?

>   - Update commit message to reflect that this change isn't strictly
>   necessary for arches w/ >32bit pte flags

I can't seem to be able to associate this with anything in the commit
message. The comment here to me reads as if this was optional (but then
for arches with <=32-bit PTE flags), yet in the description I can't spot
anything to the same effect. Recall that it was said before that on x86
we also have flags extending beyond bit 31, just that we pass them
around in a compacted manner (which, as Andrew has been suggesting, may
be undue extra overhead).

Jan

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