linux-kernel - Re: [PATCH v2 6/7] x86/mm: remove p4d

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Message-ID: <Z-uTzP2CpG9ntXY8@gmail.com>
Date: Tue, 1 Apr 2025 09:20:44 +0200
From: Ingo Molnar <mingo@...nel.org>
To: Baoquan He <bhe@...hat.com>
Cc: akpm@...ux-foundation.org, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, yanjun.zhu@...ux.dev, x86@...nel.org
Subject: Re: [PATCH v2 6/7] x86/mm: remove p4d_leaf definition


* Baoquan He <bhe@...hat.com> wrote:

> > So the above comment should have said '256 TB' pages, unless 
> > there's some naming weirdness I missed.
> 
> Hmm, there could be misunderstanding here. In 5-level paging, PGD is 
> the highest level, P4D is the next level of PGD. You may have 
> reversed their order.

Erm, yes indeed I flipped those two, so the correct table should be:

  - level 0:                 4K pages
  - level 1: 512x    4K =   2MB 'large' pages
  - level 2: 512x   2MB =   1GB 'huge' pages
  - level 3: 512x   1GB = 512GB 'P4D' pages
  - level 4: 512x 512GB = 256TB 'PGD' pages

I'm wondering whether 512GB pages will be called 'terapages'. ;-)

Thanks,

	Ingo