From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Jared Hulbert" Subject: Re: [patch 4/6] xip: support non-struct page backed memory Date: Mon, 3 Mar 2008 07:44:50 -0800 Message-ID: <6934efce0803030744w6946e74an113d359c398415cd@mail.gmail.com> References: <20080118045649.334391000@suse.de> <20080118045755.735923000@suse.de> <6934efce0803010014p2cc9a5edu5fee2029c0104a07@mail.gmail.com> <47CBB44D.7040203@de.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: npiggin@suse.de, "Linus Torvalds" , "Andrew Morton" , mschwid2@linux.vnet.ibm.com, heicars2@linux.vnet.ibm.com, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org To: carsteno@de.ibm.com Return-path: Received: from el-out-1112.google.com ([209.85.162.180]:9358 "EHLO el-out-1112.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754792AbYCCPow (ORCPT ); Mon, 3 Mar 2008 10:44:52 -0500 Received: by el-out-1112.google.com with SMTP id v27so110225ele.17 for ; Mon, 03 Mar 2008 07:44:51 -0800 (PST) In-Reply-To: <47CBB44D.7040203@de.ibm.com> Content-Disposition: inline Sender: linux-fsdevel-owner@vger.kernel.org List-ID: > Is there a chance virt_to_phys() can be fixed on arm? It looks like a > simple page table walk to me. Are there functions already available for doing a page table walk? If so it could be done. I'd like that. If somebody could point me in the right direction I'd appreciate it. It might be a problem because today the simple case for virt_to_phys() just subtracts 0x20000000 to go from 0xCXXXXXXX to 0xAXXXXXXX. So it could have a negative performance if we complicate it. Is it possible that it might be easier to fix this if we changed ioremap()? I got the impression that ioremap() on ARM ends up placing ioremap()'ed memory in the middle of the 0xCXXXXXXX range that is valid for RAM.