Re: [RFC PATCH 10/34] x86: mm: carve out the generic compile-time folded pgtable case in effective_prot()

Dave Hansen <[email protected]> Mon, 13 Jul 2026 07:55:09 -0700
Newsgroups org.kernel.vger.linux-csky,dev.linux.lists.loongarch,org.infradead.lists.kvm-riscv,org.infradead.lists.linux-riscv,org.kernel.vger.linux-arch,org.kernel.vger.linux-kernel,org.kernel.vger.linux-m68k,org.kernel.vger.linux-mips,org.kernel.vger.linux-openrisc,org.kvack.linux-mm
Message-ID <[email protected]>
On 7/13/26 07:41, David Hildenbrand (Arm) wrote:
> Essentially, we have to teach x86 code to ignore levels that are folded (e.g.,
> pgd, p4d) and start collecting effective prots from the actual first non-folded
> level.

I guess that's what the series really comes down to.

The model is moving from (using 3-level PAE as an example):

 PGD => ...folding => PMD => PTE

to

 ...folding => PUD => PMD => PTE

Right?

That's actually not the worst thing in the world, but it is a pretty big
change. It moves the software model away from how the hardware works.
It's a bit more grand than I thought from glancing at the cover letter.