Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262602AbVCJNtj (ORCPT ); Thu, 10 Mar 2005 08:49:39 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262606AbVCJNtj (ORCPT ); Thu, 10 Mar 2005 08:49:39 -0500 Received: from [192.139.46.150] ([192.139.46.150]:3789 "EHLO jaguar.mkp.net") by vger.kernel.org with ESMTP id S262602AbVCJNtd (ORCPT ); Thu, 10 Mar 2005 08:49:33 -0500 To: Andrew Morton Cc: hch@infradead.org, linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [patch -mm series] ia64 specific /dev/mem handlers References: <16923.193.128608.607599@jaguar.mkp.net> <20050222020309.4289504c.akpm@osdl.org> <20050222175225.GK28741@parcelfarce.linux.theplanet.co.uk> <20050222112513.4162860d.akpm@osdl.org> <20050222153456.502c3907.akpm@osdl.org> <20050223223404.GA21383@infradead.org> <20050309225516.55195ddc.akpm@osdl.org> From: Jes Sorensen Date: 10 Mar 2005 08:49:22 -0500 In-Reply-To: <20050309225516.55195ddc.akpm@osdl.org> Message-ID: User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.3 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1777 Lines: 40 >>>>> "Andrew" == Andrew Morton writes: Andrew> Jes Sorensen wrote: >> Convert /dev/mem read/write calls to use arch_translate_mem_ptr if >> available. Needed on ia64 for pages converted fo uncached mappings >> to avoid it being accessed in cached mode after the conversion >> which can lead to memory corruption. Introduces PG_uncached page >> flag for marking pages uncached. Andrew> For some reason this patch still gives me the creeps. Maybe Andrew> it's because we lose a page flag for something so obscure. Andrew> Nothing ever clears PG_uncached. We'll end up with every page Andrew> in the machine marked as being uncached. Actually there's restrictions to how many pages are getting converted as converting pages over from cached to uncached isn't trivial on ia64. Andrew> But then, nothing ever sets PG_uncached, either. Is there Andrew> some patch which you're hiding from me? Actually I posted that earlier, but it must have gotten lost in the noise. It's part of the genalloc/mspec patchset. I'll send it to you directly. Andrew> If a page is marked uncached then it'll remain marked as Andrew> uncached even after it's unmapped. Or will it? Would like to Andrew> see the other patch, please. Coming your way in a jiffy. Andrew> We should add PG_uncached checks to the page allocator. Is Andrew> this OK? I don't see any problems with that. The way it's meant to be used is that once pages are converted over, they don't go back into the allocator. Cheers, Jes - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/