From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out187-13.us.a.mail.aliyun.com (out187-13.us.a.mail.aliyun.com [47.90.187.13]) (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 30380195390 for ; Thu, 19 Sep 2024 07:48:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=47.90.187.13 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726732093; cv=none; b=Q0Wd56FwxgSOzoy08WB5S2VuiaXu+67T5Ce7sgKWGS5WDx7CyoL+1mgD1WWhTIA3vufxvM2qe3Z6MQVSwvc1ffwba30mgQgjIgfg+q7TlI7/8+96hl3s7zQqpiD92TkWCxdHOK63rHAMu3qdMg1W2XlvYBQif7VNToTEBCsJE6g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726732093; c=relaxed/simple; bh=BIIS+CjQk3qH1Dkl+KdaXyMXVz9ppYb9EoGgxjvqnLw=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=KfnrfbQZJIqFRCeeMYp/6e6Bf1an5Wbtw2/l5DSH9bN64Sg9Ye8YpvxujzwfTKA/Ss4APvsnN1h95HC6XUObyFT4QW52yIeehM9zEk1Ld4+TUa8g+RhtRl9RDEZ7iBr0Q69W4g5vqjcR2Z7B63ny71dCI8E0HXM0jTS9f+LI3tM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=antgroup.com; spf=pass smtp.mailfrom=antgroup.com; dkim=pass (1024-bit key) header.d=antgroup.com header.i=@antgroup.com header.b=EddgHVqN; arc=none smtp.client-ip=47.90.187.13 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=antgroup.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=antgroup.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=antgroup.com header.i=@antgroup.com header.b="EddgHVqN" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=antgroup.com; s=default; t=1726732070; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=WaWmR/2gbJuAnFjeJ7UqO4YR7c/p0mLjhuVApW14H/8=; b=EddgHVqNPCcj9ffUtQdDmaiMC1CCRpHTZtXarkmjINP6eVBorwYcdVuQlsuUpTiv0aVal1A+ffVD5HhyFAZcoUeCXIIGLnMS3ZOGHzM03EcyJQ9J2rB4CbUVzgQkdeBbsEfP7cnxLUBypVGwCeXCFA3fP/FgLxv04ATE2EtSSm4= Received: from 30.230.84.113(mailfrom:tiwei.btw@antgroup.com fp:SMTPD_---.ZNEik1g_1726732064) by smtp.aliyun-inc.com; Thu, 19 Sep 2024 15:47:49 +0800 Message-ID: <75b42537-e895-4c3a-85b5-3c9beab3e149@antgroup.com> Date: Thu, 19 Sep 2024 15:47:42 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] um: Remove 3-level page table support on i386 To: Benjamin Berg , Johannes Berg , richard@nod.at, anton.ivanov@cambridgegreys.com Cc: linux-um@lists.infradead.org, linux-kernel@vger.kernel.org References: <20240918061702.614837-1-tiwei.btw@antgroup.com> <0a73298f1c0ed189046360ea867e6da32276381c.camel@sipsolutions.net> <627bd11a7fe69fed02719c2ecf5370b59328e80d.camel@sipsolutions.net> Content-Language: en-US From: "Tiwei Bie" In-Reply-To: <627bd11a7fe69fed02719c2ecf5370b59328e80d.camel@sipsolutions.net> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 2024/9/19 15:22, Benjamin Berg wrote: > On Thu, 2024-09-19 at 08:54 +0200, Johannes Berg wrote: >> On Wed, 2024-09-18 at 14:17 +0800, Tiwei Bie wrote: >>> The highmem support has been removed by commit a98a6d864d3b ("um: >>> Remove broken highmem support"). The 2-level page table is >>> sufficient >>> on UML/i386 now. Remove the 3-level page table support on UML/i386 >>> which is still marked as experimental. >>> >> >> No real objection, but with the 4-level page table work on 64-bit >> pending as well (which likely conflicts), I wonder if we should just >> remove 3-level *entirely*? Fine with me in either way. Keeping only one page table implementation on UML/x86_64 may require smaller maintenance effort. > > Fine with me. There is only the tiny advantage of saving a few pages of > memory for each process. I just erred on the side of keeping it in case > anyone is cares to the option … > > I'll resubmit the patchset without 3-level support then, possibly on > top of this patch. Thanks! :) Regards, Tiwei > On the assumption that no one actually cares about > 3-level page tables on x86_64. > > Benjamin