From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lithops.sigma-star.at (mailout.nod.at [116.203.167.152]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 11A9818FDBE; Wed, 10 Sep 2025 20:33:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=116.203.167.152 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757536397; cv=none; b=EIknayxSztkbtGhJ4j3ipGR8TF6irHcpmC2JPWj2qUtSWfogo4nmXgsm3W56gqyvcTCLa6gly+ao0Ci9/ShJl56FVlMNyvYjLiobuPxoIIBbXUl/vo9LrkO14Mxptjd23gSAGQUVMwAMMRdTmZySUQY9lFhLVYIfye5xjEKIdR8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757536397; c=relaxed/simple; bh=Xn32CgfsCdcgiZc5xVsldvxbovwbLiKF6pDU6aeqlX8=; h=Date:From:To:Cc:Message-ID:In-Reply-To:References:Subject: MIME-Version:Content-Type; b=SIx47eboTwhbXTcdGlaph7BITRcgGac3ROWI8oRR+9Cp+f/bhSF7nExkrXSjLWjate0eoWjek6w6NvYUVnK0WYZHzDmWs2SF2hAndqwRMYpxI3swLtEGDuBhuQGCb8s72tFGEPV9zRBJ24DakThdlIM15yc0lNhEJqQ14NuZWh4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=nod.at; spf=fail smtp.mailfrom=nod.at; arc=none smtp.client-ip=116.203.167.152 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=nod.at Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=nod.at Received: from localhost (localhost [127.0.0.1]) by lithops.sigma-star.at (Postfix) with ESMTP id 511D5CE34D; Wed, 10 Sep 2025 22:33:07 +0200 (CEST) Received: from lithops.sigma-star.at ([127.0.0.1]) by localhost (lithops.sigma-star.at [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id aSKreuvdlGXI; Wed, 10 Sep 2025 22:33:06 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by lithops.sigma-star.at (Postfix) with ESMTP id 4BFD3CE34E; Wed, 10 Sep 2025 22:33:06 +0200 (CEST) Received: from lithops.sigma-star.at ([127.0.0.1]) by localhost (lithops.sigma-star.at [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id YO9RM-IU3T_L; Wed, 10 Sep 2025 22:33:06 +0200 (CEST) Received: from lithops.sigma-star.at (lithops.sigma-star.at [195.201.40.130]) by lithops.sigma-star.at (Postfix) with ESMTP id 082B5CE34D; Wed, 10 Sep 2025 22:33:06 +0200 (CEST) Date: Wed, 10 Sep 2025 22:33:05 +0200 (CEST) From: Richard Weinberger To: Dave Hansen Cc: Arnd Bergmann , ksummit , linux-kernel , linux-arm-kernel , linuxppc-dev , linux-mips , linux-mm , imx , Christophe Leroy , Lucas Stach , Linus Walleij , Geert Uytterhoeven , Ankur Arora , David Hildenbrand , Mike Rapoport , Lorenzo Stoakes , Matthew Wilcox , Andrew Morton , "Liam R. Howlett" , vbabka , Suren Baghdasaryan , Ira Weiny , Nishanth Menon , heiko , Alexander Sverdlin , "Chester A. Unal" , Sergio Paracuellos , Andreas Larsson Message-ID: <640041197.22387.1757536385810.JavaMail.zimbra@nod.at> In-Reply-To: References: <4ff89b72-03ff-4447-9d21-dd6a5fe1550f@app.fastmail.com> <497308537.21756.1757513073548.JavaMail.zimbra@nod.at> Subject: Re: [TECH TOPIC] Reaching consensus on CONFIG_HIGHMEM phaseout Precedence: bulk X-Mailing-List: imx@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Mailer: Zimbra 8.8.12_GA_3807 (ZimbraWebClient - FF141 (Linux)/8.8.12_GA_3809) Thread-Topic: Reaching consensus on CONFIG_HIGHMEM phaseout Thread-Index: qX92QwLBi0un/69XQpQP6tb4aScRlQ== Dave, ----- Urspr=C3=BCngliche Mail ----- > Von: "Dave Hansen" >> Even with a new memory split, which could utilize most of the >> available memory, I expect there to be issues with various >> applications and FPGA device drivers. > I'd be really curious what the _actual_ issues would be with a > non-standard split. There are a lot of "maybe" problems and solutions > here, but it's hard to move forward without known practical problems to > tackle. >=20 > Has anybody run into actual end user visible problems when using one of > weirdo PAGE_OFFSET configs? In the past I saw that programs such as the Java Runtime (JRE) ran into address space limitations due to a 2G/2G split on embedded systems. Reverting to a 3G/1G split fixed the problems. Thanks, //richard