Re: [PATCH RFC v2 14/20] x86: mm: skip pud setup when using generic compile-time folded pagetable
Yeoreum Yun <[email protected]> Fri, 24 Jul 2026 12:49:45 +0100
| Newsgroups | org.kernel.vger.linux-openrisc,dev.linux.lists.loongarch,org.infradead.lists.kvm-riscv,org.infradead.lists.linux-riscv,org.kernel.vger.kvm,org.kernel.vger.linux-arch,org.kernel.vger.linux-kernel,org.kernel.vger.linux-mips,org.kvack.linux-mm |
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| Message-ID | <[email protected]> |
On Wed, Jul 22, 2026 at 01:22:04PM -0700, Dave Hansen wrote: > On 7/22/26 13:18, Yeoreum Yun wrote: > > Sorry. But do you mean check with cpu_feature_enabled() not with > > boot_cpu_has()? > > IIRC, the boot_cpu_has() doesn't use the DISABLE_MASK_BIT_SET() but > > uses REQUIRED_MASK_BIT_SET() and I don't expect it wouldn't make > > an optimisation to constant check which is contrast to DISABLE_MASK_BIT_SET(). > > Ahh, yes. I forgot about that nuance! Moving to cpu_feature_enabled() > would be great! When I see again, using cpu_feature_enabled(), this would give a chance to optimisation when the feature disabled and there would be no harm for when feature enabled since cpu_feature_enabbled() also fallback to boot_cpu_has(). So, it might be good to change with cpu_feature_enabled() as we discussed. @Dave, Should I send above change separately or include it in this patch? -- Sincerely, Yeoreum Yun