linux-kernel - Re: [PATCH 1/4] x86/mm: Add a few comments

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Message-ID: <CAHk-=wg8UrshBBLioF0+FaJvAkSTRkH3-aqKT3eAWHtBp57hxw@mail.gmail.com>
Date:   Thu, 10 Nov 2022 08:22:54 -0800
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     x86@...nel.org, dave.hansen@...el.com,
        linux-kernel@...r.kernel.org, oliver.sang@...el.com
Subject: Re: [PATCH 1/4] x86/mm: Add a few comments

On Thu, Nov 10, 2022 at 4:58 AM Peter Zijlstra <peterz@...radead.org> wrote:
>
> It's a shame to hide useful comments in Changelogs, add some to the
> code.
>
> Shamelessly stolen from commit:

When the comment says how the image is mapped into two places,
wouldn't it be good to also have the reason *why* rather than just
what..

That said, my real commentary for this patch set is not that
particular instance, but the bigger picture - that this code is still
a bit opaque as to why these things are done.

Do we need any of those alias passes at all for pure protection bit
changes? I thought we only did these because things like cacheability
bits have to be in sync due to machine checks etc?

Or am I missing some case where writability matters too?

                   Linus