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[209.85.128.50]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-b07830acd07sm61516166b.32.2025.09.09.15.31.15 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 09 Sep 2025 15:31:15 -0700 (PDT) Received: by mail-wm1-f50.google.com with SMTP id 5b1f17b1804b1-45de6490e74so25913655e9.2 for ; Tue, 09 Sep 2025 15:31:15 -0700 (PDT) X-Forwarded-Encrypted: i=1; AJvYcCUhQ8PpatFdPQcz7LjFCwJbbAgTzDXz4VpOLjZRsbwZ8KYCWf30sdQ/qlDcMatIDjoOepQ=@lists.linux.dev X-Received: by 2002:a05:6402:4412:b0:61e:a13a:27b8 with SMTP id 4fb4d7f45d1cf-623729cb58cmr11071027a12.1.1757456686093; Tue, 09 Sep 2025 15:24:46 -0700 (PDT) Precedence: bulk X-Mailing-List: imx@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <4ff89b72-03ff-4447-9d21-dd6a5fe1550f@app.fastmail.com> In-Reply-To: From: Linus Torvalds Date: Tue, 9 Sep 2025 15:24:29 -0700 X-Gmail-Original-Message-ID: X-Gm-Features: Ac12FXyoXbbHUJtrfKhAFeDlVJsB9IiUaRxuYQBQJQyqpHDKK1GQ8JtkX5zx-HA Message-ID: Subject: Re: [TECH TOPIC] Reaching consensus on CONFIG_HIGHMEM phaseout To: "H. Peter Anvin" 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 , =?UTF-8?Q?Heiko_St=C3=BCbner?= , Alexander Sverdlin , "Chester A. Unal" , Sergio Paracuellos , Andreas Larsson Content-Type: text/plain; charset="UTF-8" On Tue, 9 Sept 2025 at 14:39, H. Peter Anvin wrote: > > 1 GB systems used highmem too, sadly. And 1 GB was the norm for a big chuck of the late 32-bit era. Well, while on x86 1GB systems did use highmem, they'd typically not use very much of it. IOW, they'd have about 900MB as lowmem (ok, I think it was 896MB to be exact), with something like 120MB highmem. So they'd either lose a bit of memory, or they'd use the 2G:2G split. Or - and I think this is the main point - they'd stay on old kernels like the ancient museum pieces they are. I'm not convinced it makes sense to have a modern kernel on a museum piece. Linus