From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Tue, 26 Aug 2014 04:41:18 +0200 (CEST) Received: from qmta06.westchester.pa.mail.comcast.net ([76.96.62.56]:34702 "EHLO qmta06.westchester.pa.mail.comcast.net" rhost-flags-OK-OK-OK-OK) by eddie.linux-mips.org with ESMTP id S27006814AbaHZClRWPUj7 (ORCPT ); Tue, 26 Aug 2014 04:41:17 +0200 Received: from omta02.westchester.pa.mail.comcast.net ([76.96.62.19]) by qmta06.westchester.pa.mail.comcast.net with comcast id jEcf1o0010QuhwU56EhBXY; Tue, 26 Aug 2014 02:41:11 +0000 Received: from [192.168.1.13] ([50.190.84.14]) by omta02.westchester.pa.mail.comcast.net with comcast id jEh91o0100JZ7Re3NEhAWZ; Tue, 26 Aug 2014 02:41:11 +0000 Message-ID: <53FBF3C3.90509@gentoo.org> Date: Mon, 25 Aug 2014 22:41:07 -0400 From: Joshua Kinard User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:31.0) Gecko/20100101 Thunderbird/31.0 MIME-Version: 1.0 To: David Daney CC: Ralf Baechle , Max Filippov , linux-xtensa@linux-xtensa.org, Chris Zankel , Marc Gauthier , linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-mips@linux-mips.org, linux-kernel@vger.kernel.org, David Rientjes , Andrew Morton , Leonid Yegoshin , Steven Hill Subject: Re: [PATCH v4 0/2] mm/highmem: make kmap cache coloring aware References: <1406941899-19932-1-git-send-email-jcmvbkbc@gmail.com> <20140825171600.GH25892@linux-mips.org> <53FBCD09.1050003@gentoo.org> <53FBD676.8080307@gmail.com> In-Reply-To: <53FBD676.8080307@gmail.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=comcast.net; s=q20140121; t=1409020871; bh=7pXsMm9PgVboL1iGLpDV+6rUik/btJU9xc6qN3NOVkI=; h=Received:Received:Message-ID:Date:From:MIME-Version:To:Subject: Content-Type; b=woViiizYhSoMoZxFMKwFdVE4btrmHicYbUTfBjegaieCk9D3SJN66OJ0SQnLt1Sy3 gL7Pmd7k+A/KZJBuFYj6Ht3ujtIliVbcIyv82IoJQcEAYe9FxiypxwLX4gZBNv1opE oAFxrtfijZNftr2GTmPjQeM98rSTgaUYjwCB5D8zedSGWOtC+zDOuYsu53lTUsh8h4 63lnsPqRgQnWb64sT/uOfikMCj6RnUV/KWL0KEDfWeLHcpbs0iia6vCIAh44NHop+1 ms4kbLZjhQ1BoDoni0y9Zm/mAN2Ki+5PGhqGbwcN/Ghb3+mq/PEH4sPQFltaYR5mjM 3z+5YcOMT1sRA== Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 42243 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: kumba@gentoo.org Precedence: bulk List-help: List-unsubscribe: List-software: Ecartis version 1.0.0 List-Id: linux-mips X-List-ID: linux-mips List-subscribe: List-owner: List-post: List-archive: X-list: linux-mips On 08/25/2014 20:36, David Daney wrote: > On 08/25/2014 04:55 PM, Joshua Kinard wrote: >> On 08/25/2014 13:16, Ralf Baechle wrote: >>> On Sat, Aug 02, 2014 at 05:11:37AM +0400, Max Filippov wrote: >>> >>>> this series adds mapping color control to the generic kmap code, allowing >>>> architectures with aliasing VIPT cache to use high memory. There's also >>>> use example of this new interface by xtensa. >>> >>> I haven't actually ported this to MIPS but it certainly appears to be >>> the right framework to get highmem aliases handled on MIPS, too. >>> >>> Though I still consider increasing PAGE_SIZE to 16k the preferable >>> solution because it will entirly do away with cache aliases. >> >> Won't setting PAGE_SIZE to 16k break some existing userlands (o32)? I use a >> 4k PAGE_SIZE because the last few times I've tried 16k or 64k, init won't >> load (SIGSEGVs or such, which panicks the kernel). >> > > It isn't supposed to break things. Using "stock" toolchains should result > in executables that will run with any page size. > > In the past, some geniuses came up with some linker (ld) patches that, in > order to save a few KB of RAM, produced executables that ran only on 4K pages. > > There were some equally astute Debian emacs package maintainers that were > carrying emacs patches into Debian that would not work on non-4K page size > systems. > > That said, I think such thinking should be punished. The punishment should > be to not have their software run when we select non-4K page sizes. The > vast majority of prepackaged software runs just fine with a larger page size. Well, it does appear to mostly work now w/ 16k PAGE_SIZE. The Octane booted into userland with just a couple of "illegal instruction" errors from 'rm' and 'mdadm'. I wonder if that's tied to a hardcoded PAGE_SIZE somewhere. Have to dig around and find something that reproduces the problem on demand. -- Joshua Kinard Gentoo/MIPS kumba@gentoo.org 4096R/D25D95E3 2011-03-28 "The past tempts us, the present confuses us, the future frightens us. And our lives slip away, moment by moment, lost in that vast, terrible in-between." --Emperor Turhan, Centauri Republic