Messages in this thread | | | Date | Tue, 15 Mar 2022 08:53:49 -0700 | From | Ira Weiny <> | Subject | Re: [PATCH 5/5] x86/pkeys: Standardize on u8 for pkey type |
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On Mon, Mar 14, 2022 at 04:49:12PM -0700, Dave Hansen wrote: > On 3/10/22 16:57, ira.weiny@intel.com wrote: > > From: Ira Weiny <ira.weiny@intel.com> > > > > The number of pkeys supported on x86 and powerpc are much smaller than a > > u16 value can hold. It is desirable to standardize on the type for > > pkeys. powerpc currently supports the most pkeys at 32. u8 is plenty > > large for that. > > > > Standardize on the pkey types by changing u16 to u8. > > How widely was this intended to "standardize" things? Looks like it may > have missed a few spots.
Sorry I think the commit message is misleading you. The justification of u8 as the proper type is that no arch has a need for more than 255 pkeys.
This specific patch was intended to only change x86. Per that goal I don't see any other places in x86 which uses u16 after this patch.
$ git grep u16 arch/x86 | grep key arch/x86/events/intel/uncore_discovery.c: const u16 *type_id = key; arch/x86/include/asm/intel_pconfig.h: u16 keyid; arch/x86/include/asm/mmu.h: u16 pkey_allocation_map; arch/x86/include/asm/pkeys.h: u16 all_pkeys_mask = ((1U << arch_max_pkey()) - 1);
> > Also if we're worried about the type needing to change or with the wrong > type being used, I guess we could just to a pkey_t typedef.
I'm not 'worried' about it. But I do think it makes the code cleaner and more self documenting.
Ira
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