Messages in this thread | | | Subject | Re: [PATCH 1/4] hugetlbfs: add arch_hugetlb_valid_size | From | Dave Hansen <> | Date | Thu, 26 Mar 2020 16:10:56 -0700 |
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On 3/26/20 2:56 PM, Mike Kravetz wrote: > Perhaps it would be best to check hugepages_supported() when parsing > hugetlb command line options. If not enabled, throw an error. This > will be much easier to do after moving all command line parsing to > arch independent code.
Yeah, that sounds sane.
> Is that a sufficient way to address this concern? I think it is a good > change in any case.
(Thanks to Kirill for pointing this out.)
So, it turns out the x86 huge page enumeration is totally buggered. X86_FEATURE_PSE is actually meaningless on 64-bit (and 32-bit PAE). All CPUs architecturally support 2MB pages regardless of X86_FEATURE_PSE and the state of CR4.PSE.
So, on x86_64 at least, hugepages_supported() should *always* return 1.
1GB page support can continue to be dependent on X86_FEATURE_GBPAGES.
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