Re: [PATCH 1/4] hugetlbfs: add arch_hugetlb_valid_size

[Christian Borntraeger]

On 25.03.20 03:58, Longpeng (Mike, Cloud Infrastructure Service Product Dept.) wrote:
[...]
> Hi Mike,
> 
> Inspired by Dave's opinion, it seems the x86-specific hugepages_supported should
> also need to use cpu_feature_enabled instead.
> 
> Also, I wonder if the hugepages_supported is correct ? There're two arch
> specific hugepages_supported:
> x86:
> #define hugepages_supported() boot_cpu_has(X86_FEATURE_PSE)
> and
> s390:
> #define hugepages_supported() (MACHINE_HAS_EDAT1)
> 
> Is it possible that x86 has X86_FEATURE_GBPAGES but hasn't X86_FEATURE_GBPAGES
> or s390 has MACHINE_HAS_EDAT2 but hasn't MACHINE_HAS_EDAT1 ?

The s390 architecture says that 

When EDAT-2 applies, the following function is available in the DAT process:
 - EDAT-1 applies.
[..]

So if the machine has EDAT-2 it also has EDAT-1.