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Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1q95Gi-0040br-Qq; Tue, 13 Jun 2023 14:45:12 +0000 Date: Tue, 13 Jun 2023 15:45:12 +0100 From: Matthew Wilcox To: Linus Walleij Cc: Andrew Morton , Jonathan Corbet , linux-mm@kvack.org, linux-doc@vger.kernel.org, Randy Dunlap , Mike Rapoport , Jonathan Cameron , Bagas Sanjaya Subject: Re: [PATCH v4] Documentation/mm: Initial page table documentation Message-ID: References: <20230613083906.757878-1-linus.walleij@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230613083906.757878-1-linus.walleij@linaro.org> X-Rspamd-Queue-Id: 240AF180006 X-Rspam-User: X-Stat-Signature: ii5c99hywaru5yhicqyw794mtethehwk X-Rspamd-Server: rspam03 X-HE-Tag: 1686667520-367258 X-HE-Meta: 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 V65qaBLp X5TUrBGRG4XI3SfQyP6bpMu9eqomCV2U+s0E/J8DndNLRKGYyE98Ml4pQttwf6zotW3NFfBCYijcVvdkqc2K2S9Xl5xOecZFyk1s2bJuEao7r9jqMXYk+qacycZTrf16T/bcxOn9f+YpzpRM= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000001, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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.