[{"id":3678380,"web_url":"http://patchwork.ozlabs.org/comment/3678380/","msgid":"","list_archive_url":null,"date":"2026-04-16T21:07:03","subject":"Re: [PATCH v1 1/3] common: memsize: add RAM size probe based on alias\n detection","submitter":{"id":6170,"url":"http://patchwork.ozlabs.org/api/people/6170/","name":"Simon Glass","email":"sjg@chromium.org"},"content":"Hi Emanuele,\n\nOn 2026-04-16T08:45:22, Emanuele Ghidoli wrote:\n> common: memsize: add RAM size probe based on alias detection\n>\n> Add probe_ram_size_by_alias() to detect RAM size by checking whether a\n> write to one address aliases to another address.\n>\n> Compared to get_ram_size(), this function allows the caller to:\n> - limit probing to a small set of required accesses\n> - avoid touching reserved or already used memory regions\n> - handle non-linear alias patterns\n>\n> On the iMX95 SoC, when used with LPDDR5, accesses beyond the end of an 8GB DDR\n> configuration do not alias to the expected linear wrap-around addresses.\n> Instead, the aliased addresses appears to follow a pattern related to the\n> DDRC bank and bank-group addresses mapping. Experimentally, the observed\n> pattern is:\n>\n> Write Read\n> y00000000 -> x0001c000\n> y00004000 -> x00018000\n> y00008000 -> x00014000\n> [...]\n>\n> common/memsize.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++\n> include/init.h | 7 +++++++\n> 2 files changed, 63 insertions(+)\n\n> diff --git a/common/memsize.c b/common/memsize.c\n> @@ -127,6 +127,62 @@ long get_ram_size(long *base, long maxsize)\n> +long probe_ram_size_by_alias(const struct ram_alias_check *checks)\n> +{\n> + long save[2];\n> + int dcache_en = dcache_status();\n\nDo we need to check for CONFIG_IS_ENABLED(SYS_DCACHE_OFF) here?\n\nReviewed-by: Simon Glass \n\nRegards,\nSimon","headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (1024-bit key;\n unprotected) header.d=chromium.org header.i=@chromium.org header.a=rsa-sha256\n header.s=google header.b=SGoIVKww;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=lists.denx.de\n (client-ip=85.214.62.61; helo=phobos.denx.de;\n envelope-from=u-boot-bounces@lists.denx.de; receiver=patchwork.ozlabs.org)","phobos.denx.de;\n dmarc=pass (p=none dis=none) header.from=chromium.org","phobos.denx.de;\n spf=pass smtp.mailfrom=u-boot-bounces@lists.denx.de","phobos.denx.de;\n\tdkim=pass (1024-bit key;\n unprotected) header.d=chromium.org header.i=@chromium.org\n header.b=\"SGoIVKww\";\n\tdkim-atps=neutral","phobos.denx.de;\n dmarc=pass (p=none dis=none) header.from=chromium.org","phobos.denx.de;\n spf=pass smtp.mailfrom=sjg@chromium.org"],"Received":["from phobos.denx.de (phobos.denx.de [85.214.62.61])\n\t(using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)\n\t key-exchange x25519)\n\t(No client certificate requested)\n\tby legolas.ozlabs.org (Postfix) with ESMTPS id 4fxVvq6hfKz1yCv\n\tfor ; Fri, 17 Apr 2026 07:07:35 +1000 (AEST)","from h2850616.stratoserver.net (localhost [IPv6:::1])\n\tby phobos.denx.de (Postfix) with ESMTP id A5C7483FC0;\n\tThu, 16 Apr 2026 23:07:32 +0200 (CEST)","by phobos.denx.de (Postfix, from userid 109)\n id F2C5383EEF; Thu, 16 Apr 2026 23:07:30 +0200 (CEST)","from mail-pf1-x429.google.com (mail-pf1-x429.google.com\n [IPv6:2607:f8b0:4864:20::429])\n (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits))\n (No client certificate requested)\n by phobos.denx.de (Postfix) with ESMTPS id 9BF7583EEF\n for ; Thu, 16 Apr 2026 23:07:28 +0200 (CEST)","by mail-pf1-x429.google.com with SMTP id\n d2e1a72fcca58-82418b0178cso14122b3a.1\n for ; Thu, 16 Apr 2026 14:07:28 -0700 (PDT)"],"X-Spam-Checker-Version":"SpamAssassin 3.4.2 (2018-09-13) on phobos.denx.de","X-Spam-Level":"","X-Spam-Status":"No, score=-2.6 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,\n DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,\n RCVD_IN_DNSWL_BLOCKED,SPF_HELO_NONE,SPF_PASS autolearn=ham\n autolearn_force=no version=3.4.2","ARC-Seal":"i=1; a=rsa-sha256; t=1776373647; cv=none;\n d=google.com; s=arc-20240605;\n b=Sxxz5+YsvlG+4CgSD877jeFPta6OyFJY4IzpW66w5R3oTOULHDoCQXgEEpt5V8VJqb\n TYft+A2G6Ryz0NDcVJekLHHLjBnTlgOFDxHrraKvrgYtfc01gvgIOFbVT9iEflvFDrV8\n 3IhKT/8nO/79z77qhJhwm4yFyLSneZuEt4vBXNz83RbjxYrKtZJeSbLO5SQkE7ijoPSB\n rw6VKA4HZfd5Cr11b+RyvSZ1DKzir1RGGniODDMBxbPlQPdXAm/A0d6q2lN7+qt+JlW5\n M9T7iX258x+M8EppDF1ZW9TGb/2TpsVXxb5GigZoOIi8IRtR2LBXGDg+Tuer2BaSzyFZ\n KdTQ==","ARC-Message-Signature":"i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com;\n s=arc-20240605;\n h=cc:to:subject:message-id:date:from:in-reply-to:references\n :mime-version:dkim-signature;\n bh=lCHrczTgAg1arX1rTBbwoFW4AgDmUUJyY+CWT808Fds=;\n fh=l/r1vsCeo0JYoY/8e+8RCaL8GrWqIw7H3MkBLAqGicU=;\n b=EqdL6m5E/NIJ7O9cD9DcCQcD20/gk4dWrr47W4lfZNeQZMHU8kcidCSjFa47CUhruD\n CTQFX5k4ayJa5d2ZOmK7T5LIYtXZHKg+jY8uG5yhcRtFo41JdHHB9qnPorY/M/l1cmrC\n +UZi362Nm0mZGLaXXEYeYS6g7ih3GsrVg4LRTDAKqLjkzcF7VMMl7rFaGuEvuR1XGdGA\n MiuWABqzXw63E3rIcv82sBYot2WWNLpPewCOKz/rlKbHTbe14Qo9aVoPSSVS+Br74ttZ\n /CJm8/rX/Mjt8r034O+4WqycWQVJGBN/ipF30bPHtYQBAxk1v2pcpwKwoYRpaynDwJuC\n hSaw==; darn=lists.denx.de","ARC-Authentication-Results":"i=1; mx.google.com; arc=none","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/relaxed;\n d=chromium.org; s=google; t=1776373647; x=1776978447; darn=lists.denx.de;\n h=cc:to:subject:message-id:date:from:in-reply-to:references\n :mime-version:from:to:cc:subject:date:message-id:reply-to;\n bh=lCHrczTgAg1arX1rTBbwoFW4AgDmUUJyY+CWT808Fds=;\n b=SGoIVKwwsa2qpKIIiyL6IaWLcntODoJyKXxrbYMQes5EFI76vHhpEA3vUg+r+ZC9PN\n I4fRWp9pjnYSO07W/aJn85vt4Qv6x2gBL2Ce49Zuf78WHqpTTix+pWoZTGUox8su8Dbt\n hlvipjuMWhEXK28LoNRR+efas7Ewo8DSkck4c=","X-Google-DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/relaxed;\n d=1e100.net; s=20251104; t=1776373647; x=1776978447;\n h=cc:to:subject:message-id:date:from:in-reply-to:references\n :mime-version:x-gm-gg:x-gm-message-state:from:to:cc:subject:date\n :message-id:reply-to;\n bh=lCHrczTgAg1arX1rTBbwoFW4AgDmUUJyY+CWT808Fds=;\n b=gkV/Dn+K3j/YAs19mLNvS7K2C9P34EiXU3SsQqo5b8x6wThbsEyXtVAOTqJnOf1q3I\n qbRlWq4ihmeAxxxt+s7u71Au+OzN/FqTz4bmVQvuKc3yPb8+NRlBAvmtwCLoNX9zk4k7\n HSFzGZvYx9YtvidkRURrDnJZZHtiZ1JaWT6ULXN0ofSBF9Xj29zo0roCUbz3TR2RSBYN\n uBw0/pBajCnbjnT8WlUqFChKPH8qZLVUXIJ1mm7ebdba5/cpUftSZ/58svHYg//113w9\n ZDppP17lfgHUxOECe0ebfh+u8L/nATpaHRTKfukH8MJ9RwdHuWoOxhrQnZKhxQu+pbFO\n vqlg==","X-Forwarded-Encrypted":"i=1;\n AFNElJ/Sdc7YXCMR0G8LwKuTth9j9lKCYNwONhsIYMLVAFexbD6gtu61f11KHVZIocoE4wFUWGSZg2g=@lists.denx.de","X-Gm-Message-State":"AOJu0YweMRbDbp1Oy6US18tx1ik3hAfcBsxnM61fcmhEo+SfU+kU+rhn\n qpeU3lbpBIb/GeCT3MkmvOzlaQ5EARUAJVIE/qY7jZswLCrFTQJU1uqcLcUNeLYT92TCtqxS73g\n mq5euN0gmlrAtmjhMk3VV3WMEAmfiZ1SH74GRTu1D","X-Gm-Gg":"AeBDietQcNcpf1u2zZsavb01vgtMlAkXfA7YnvHqMsYtAM8PiddxP+64x2C6UfG4kbC\n UHXbVK5tOyudKgoQvBf1WV3FJZ0iyUOAO9brYjjPi+rMIGFHdxZVEa2jkJb0IKM6PdfVmiTByF/\n OStzGnPvSGqGKf9kyacCV96N2wm5hL1chQU+f4oPpejFRmAFIkWAbpDCldoXSCtsDu+ZKNLaw3E\n wJvyYATq0lvGVXMFb/dLnhStqCVGBq6u2n1GI8rNzCVNLjItpwJ8IhYKUSAnXqLEkNVh28xOFMs\n ttP5Qo5F5imRYBquRKpr","X-Received":"by 2002:a05:6a00:c89:b0:82f:592f:2ed7 with SMTP id\n d2e1a72fcca58-82f8890d526mr931402b3a.45.1776373647101; Thu, 16 Apr 2026\n 14:07:27 -0700 (PDT)","MIME-Version":"1.0","References":"<20260416084535.1490476-1-ghidoliemanuele@gmail.com>\n <20260416084535.1490476-2-ghidoliemanuele@gmail.com>","In-Reply-To":"<20260416084535.1490476-2-ghidoliemanuele@gmail.com>","From":"Simon Glass ","Date":"Fri, 17 Apr 2026 09:07:03 +1200","X-Gm-Features":"AQROBzCgSbXa8LPLitglm-VGTOgojPsljEXJP-ttnijStgAUD3m-4TCW8KK1WU0","Message-ID":"\n ","Subject":"Re: [PATCH v1 1/3] common: memsize: add RAM size probe based on alias\n detection","To":"ghidoliemanuele@gmail.com","Cc":"Tom Rini , Stefano Babic ,\n Fabio Estevam ,\n \"NXP i.MX U-Boot Team\" ,\n Francesco Dolcini ,\n Emanuele Ghidoli , Peng Fan ,\n Alice Guo , Sumit Garg ,\n Simon Glass , u-boot@lists.denx.de","Content-Type":"text/plain; charset=\"UTF-8\"","X-BeenThere":"u-boot@lists.denx.de","X-Mailman-Version":"2.1.39","Precedence":"list","List-Id":"U-Boot discussion ","List-Unsubscribe":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","Errors-To":"u-boot-bounces@lists.denx.de","Sender":"\"U-Boot\" ","X-Virus-Scanned":"clamav-milter 0.103.8 at phobos.denx.de","X-Virus-Status":"Clean"}}]