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[95.233.134.55]) by smtp.gmail.com with ESMTPSA id x5-20020adff645000000b0031276f8be22sm3092993wrp.97.2023.06.20.18.10.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 20 Jun 2023 18:10:21 -0700 (PDT) From: "Fabio M. De Francesco" To: Linus Walleij , Andrew Morton , Jonathan Corbet Cc: linux-mm@kvack.org, linux-doc@vger.kernel.org, Matthew Wilcox , Randy Dunlap , Mike Rapoport , Jonathan Cameron , Bagas Sanjaya Subject: Re: [PATCH v5] Documentation/mm: Initial page table documentation Date: Wed, 21 Jun 2023 03:10:19 +0200 Message-ID: <13291493.dW097sEU6C@suse> In-Reply-To: References: <20230614072548.996940-1-linus.walleij@linaro.org> <3045029.CbtlEUcBR6@suse> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" X-Rspam-User: X-Stat-Signature: jhg6nz5djh16jnrhb9bz1sbh4nm37kqf X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 05B3DC0013 X-HE-Tag: 1687309823-526587 X-HE-Meta: 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 TOPW8cSV bywZkgwPN6106jygqENqrm6ietO+twhFeDpFjoOk6p2QI/dA2OCiAkpGQpkianwSmu12u8Fh22/1x96uurTxTURi5RXOGpuQCYcdez5Gay86nYD3vfI/WPWMGTireCvX4JrXINov0DznF7N3FpKOJqtWqx/J/yO0dmxrml2gbXVyqRgmPdzHjPMrXCIYeyGOIYPvIYI55Ro2ntJH9FgSBDZ1tmn4KiSgRbhRhO7QhYaOkaMA2YzwIMRr4Qz0RpWJSL2TCoVVDbItkJwVQRQTE2yvqQIodxFelAJV7TVwq/Bvi+wUkEYYmaSBVbKAQ8hL9t5c2ebEveI1im4lu1G2P48Qnlk90MOuAqIoM/qCVNPu4q4GjAnExPmxF35swByZEFdFwRsYr4qiP4hpEhpysnvr+um/BEcDR9mzxMEx4g5YbzZxBsK/XH4L9EfzvyYTLpbCEAfkk2cokig0= X-Bogosity: Ham, tests=bogofilter, spamicity=0.001398, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On luned=C3=AC 19 giugno 2023 10:16:56 CEST Linus Walleij wrote: > On Sun, Jun 18, 2023 at 3:16=E2=80=AFPM Fabio M. De Francesco >=20 > wrote: > > I am writing to express my dissent regarding the proposal to add basic > > information about the role of hierarchical (multi-level) page tables in > > mapping virtual memory to physical page frames. [...] =20 > Assuming that newcomers to the Linux kernel have formal academic > background or specifically operating system education is a bit thick > IMO, suffice to read pages 108-111 of Glyn Moody's book > "Rebel Code" about the background of the network maintainer. > There are a whole bunch of random people attracted to Linux > development. Linus, I must admit that I have had a change of heart regarding the necessity of t= his=20 documentation. This change came about after reading Jon's reply, as well as your own. However, it wasn't just because of the two of you. It was mainly due to my= =20 conversations with some colleagues I work with, who hold M.Sc. degrees in=20 Computer Science.=20 Despite not having a formal background in CS or CE myself, I have taken the= =20 time to self-teach the subject matter, which I expected them to be well-ver= sed=20 in. To my surprise, they only have a vague understanding of page tables and the= =20 fact that processes use addresses that may not correspond to physical=20 locations. That's about it! Hence, I now fully support your initiative and want to express my gratitude= =20 for undertaking this task. The only thing I would prefer not to see is the historical reference to the= =20 first implementation of hierarchical page tables. After all, many concepts= =20 implemented in Linux are derived or adapted from existing knowledge or=20 implementations in other kernels. However, I can also understand why you=20 prefer to have it as an introduction to the subject. Once again thanks, =46abio