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Peter Anvin" To: Linus Torvalds CC: Arnd Bergmann , ksummit@lists.linux.dev, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, linux-mips@vger.kernel.org, linux-mm@kvack.org, imx@lists.linux.dev, Christophe Leroy , Richard Weinberger , Lucas Stach , Linus Walleij , Geert Uytterhoeven , Ankur Arora , David Hildenbrand , Mike Rapoport , Lorenzo Stoakes , Matthew Wilcox , Andrew Morton , "Liam R. Howlett" , Vlastimil Babka , Suren Baghdasaryan , Ira Weiny , Nishanth Menon , =?ISO-8859-1?Q?Heiko_St=FCbner?= , Alexander Sverdlin , "Chester A. Unal" , Sergio Paracuellos , Andreas Larsson Subject: Re: [TECH TOPIC] Reaching consensus on CONFIG_HIGHMEM phaseout User-Agent: K-9 Mail for Android In-Reply-To: References: <4ff89b72-03ff-4447-9d21-dd6a5fe1550f@app.fastmail.com> Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: E015140011 X-Stat-Signature: f1napkjgofz3ugcxxeuerc8ot91yxg8j X-Rspam-User: X-Rspamd-Server: rspam09 X-HE-Tag: 1757457571-527578 X-HE-Meta: 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 f8XCf4Md kY/xvXo8PbZHRJi0YoM3RWCkYFIeg9taZsAH6+C4nKYA6PpmB/IOazMewZJ2Ls5K8D00FXOPNFZ0zMqvZ1fa8GoX15G1QDVZ52rNGGdW/WYAKt2fH/Lp5j38pY5gVCj4YHLUNtYxoSDNg+B2Giqw9BK2PGR2yrQ1YNxQ3/3iSYTYeRMRONuLN7rNwBTwWNJY+7x2mZ9y2Mz6eZBhOLPEgjnfheWBb1rUeZ1+pasHvgjrK/XVjpLuQEvjJP1EHQXiFRYNX4W+YYEpLzjXkPZRGvp3RKimb4jGV5J4kaHpiupwEn2u2mfpbE+EzydKUnFkWctUOvath8t0DYSQzKfYsIyM1WN4e1kqBwsC3DApKqBSeSR9yVVqhxc7LEzk8wtwQ5TsIRx0d6y3Cu1gG+k9NRJa6lvjVbkRpAZRuZaDkWKsv2GTFa0yrqIoowAVi3erGvbERwU/PfkqCdT91BLi5IVoTsM4bhtpSjcQBHlBXp4OexeU= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On September 9, 2025 3:24:29 PM PDT, Linus Torvalds wrote: >On Tue, 9 Sept 2025 at 14:39, H=2E Peter Anvin wrote: >> >> 1 GB systems used highmem too, sadly=2E And 1 GB was the norm for a big= chuck of the late 32-bit era=2E > >Well, while on x86 1GB systems did use highmem, they'd typically not >use very much of it=2E > >IOW, they'd have about 900MB as lowmem (ok, I think it was 896MB to be >exact), with something like 120MB highmem=2E > >So they'd either lose a bit of memory, or they'd use the 2G:2G split=2E > >Or - and I think this is the main point - they'd stay on old kernels >like the ancient museum pieces they are=2E > >I'm not convinced it makes sense to have a modern kernel on a museum piec= e=2E > > Linus > Certainly=2E And the 2:2 split is probably the right thing for the old mac= hines anyway=2E