From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Wed, 27 Aug 2014 03:04:51 +0200 (CEST) Received: from qmta04.emeryville.ca.mail.comcast.net ([76.96.30.40]:48722 "EHLO qmta04.emeryville.ca.mail.comcast.net" rhost-flags-OK-OK-OK-OK) by eddie.linux-mips.org with ESMTP id S27006947AbaH0BEuBgF0m (ORCPT ); Wed, 27 Aug 2014 03:04:50 +0200 Received: from omta18.emeryville.ca.mail.comcast.net ([76.96.30.74]) by qmta04.emeryville.ca.mail.comcast.net with comcast id jd1B1o0021bwxycA4d4iEW; Wed, 27 Aug 2014 01:04:42 +0000 Received: from [192.168.1.13] ([50.190.84.14]) by omta18.emeryville.ca.mail.comcast.net with comcast id jd4f1o0060JZ7Re8ed4gS4; Wed, 27 Aug 2014 01:04:42 +0000 Message-ID: <53FD2E9E.6050809@gentoo.org> Date: Tue, 26 Aug 2014 21:04:30 -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> <53FBF3C3.90509@gentoo.org> <53FCC7CB.8010701@gmail.com> In-Reply-To: <53FCC7CB.8010701@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=1409101482; bh=QEcqHLB2Qj0nWb/PAGDupfnQrf8WDLt3pVkv1VeCwks=; h=Received:Received:Message-ID:Date:From:MIME-Version:To:Subject: Content-Type; b=J7K3DVnHyWsS1BpV4nXB5WNo9ZD5FATB4l2BbUoY0Xag+BLSCCJyEMEfQWlvWVtGm 7WldjeeIohsN1SaZh5L8iPacsph3hWesxLBk7EPezuP2UX0APcNCjKyDoLpd25/Csm AsV/UqC0CigSXzmtdiGgV4bNXt3CUC3AMpvEHbj/tmm7fV0rsJV02NqlK1tZf85lq+ UXexhT0I7isyMMPb3+ZKTARto7Wf3i2tpp7HvMGCcg60iYUxYl4DG2oGNwjFIYXKaU oRbPW5wZYAZU06RhaYilGQo/SJfdJbHpixOz5SaacHFAna9x6VfzeaMNQPdZPP4gnP AlB+ERnvKy3QA== 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: 42270 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 08/26/2014 13:45, David Daney wrote: > On 08/25/2014 07:41 PM, Joshua Kinard wrote: >> 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. >> > > What does the output of "readelf -lW" look like for the failing programs? > If the "Offset" and "VirtAddr" constraints for the LOAD Program Headers are > not possible to achieve with the selected PAGE_SIZE, you will see problems. > A "correct" toolchain will generate binaries that work with any PAGE_SIZE up > to 64K. Well, I recently rebuilt shash, so that might've changed things. But, running readelf -lW on shash core dumped readelf itself on the first invocation (with a SIGBUS instead of SIGILL). So I instead ran readelf -lW on itself, which hasn't been recently rebuilt: # readelf -lW /usr/bin/shash Bus error (core dumped) # readelf -lW /usr/bin/readelf Elf file type is EXEC (Executable file) Entry point 0x402590 There are 11 program headers, starting at offset 52 Program Headers: Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align PHDR 0x000034 0x00400034 0x00400034 0x00160 0x00160 R E 0x4 INTERP 0x000194 0x00400194 0x00400194 0x0000d 0x0000d R 0x1 [Requesting program interpreter: /lib/ld.so.1] REGINFO 0x0001c4 0x004001c4 0x004001c4 0x00018 0x00018 R 0x4 LOAD 0x000000 0x00400000 0x00400000 0x72338 0x72338 R E 0x10000 LOAD 0x0728c8 0x004828c8 0x004828c8 0x01834 0x03d88 RW 0x10000 DYNAMIC 0x0001dc 0x004001dc 0x004001dc 0x000e0 0x000e0 RWE 0x4 NOTE 0x0001a4 0x004001a4 0x004001a4 0x00020 0x00020 R 0x4 GNU_EH_FRAME 0x0722c0 0x004722c0 0x004722c0 0x00024 0x00024 R 0x4 GNU_RELRO 0x0728c8 0x004828c8 0x004828c8 0x00738 0x00738 R 0x1 PAX_FLAGS 0x000000 0x00000000 0x00000000 0x00000 0x00000 0x4 NULL 0x000000 0x00000000 0x00000000 0x00000 0x00000 0x4 Section to Segment mapping: Segment Sections... 00 01 .interp 02 .reginfo 03 .interp .note.ABI-tag .reginfo .dynamic .hash .dynsym .dynstr .gnu.version .gnu.version_r .init .text .MIPS.stubs .fini .rodata .eh_frame_hdr .eh_frame 04 .ctors .dtors .jcr .data.rel.ro .data .rld_map .got .sdata .sbss .bss 05 .dynamic 06 .note.ABI-tag 07 .eh_frame_hdr 08 .ctors .dtors .jcr .data.rel.ro 09 10 -- 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