Re: [PATCH v4] Documentation/mm: Initial page table documentation

[Matthew Wilcox <willy@infradead.org>]

On Tue, Jun 13, 2023 at 10:39:06AM +0200, Linus Walleij wrote:
> +Paged virtual memory was invented along with virtual memory as a concept in
> +1962 on the Ferranti Atlas Computer which was the first computer with paged
> +virtual memory. The feature migrated to newer computers and became a de facto
> +feature of all Unix-like systems as time went by. In 1985 the feature was
> +included in the Intel 80386, which was the CPU Linux 1.0 was developed on.

I still don't think the origin story is useful.  It's trivia and doesn't
help someone understand what they need to know.

> +Page tables map virtual addresses as seen by the CPU program counter into
> +physical addresses as seen on the external memory bus.

This makes it sound like virtual addresses are only used for
instructions.  I had better wording earlier, but there's no point in
repeating it.  Just: I dissent. 

> +Linux defines page tables as a hierarchy which is currently five levels in
> +height. The target architecture code for each supported architecture will then
> +map this to the restrictions of the target hardware.

The word "target" isn't adding any value in this paragraph.

Honestly, I don't like much about this document.  The writing is
flabby and untargetted.  Much of my last review was ignored.  I'm just
going to stop here since I have low confidence that any suggestions
would be incorporated.