From mboxrd@z Thu Jan 1 00:00:00 1970 Received: by zproxy.gmail.com with SMTP id n29so402143nzf for ; Fri, 28 Oct 2005 00:59:08 -0700 (PDT) Message-ID: <6934efce0510280059i4c7483areee8432b62533cab@mail.gmail.com> Date: Fri, 28 Oct 2005 00:59:08 -0700 From: Jared Hulbert Subject: Re: VM_XIP Request for comments In-Reply-To: <20051027190933.GC16211@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Content-Disposition: inline References: <6934efce0510251542j66c0a738qe3c37fe56aaaaf2d@mail.gmail.com> <20051027190933.GC16211@infradead.org> Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Hellwig Cc: linux-mm@kvack.org List-ID: On 10/27/05, Christoph Hellwig wrote: > On Tue, Oct 25, 2005 at 03:42:25PM -0700, Jared Hulbert wrote: > > What would it take to get this first patch in the kernel? > > > > The reason for the first patch is in the second patch, which I will > > try to get into the kernel list. With this mmap()'ed files can be > > used directly from flash when possible and COW's it when necessary.. > > Can't you use the XIP infrastructure we already have? Grep for > CONFIG_XIP and CONFIG_EXT2_FS_XIP I can't find CONFIG_XIP. But I assume you are talking about filemap_xip.c and Documentation/filesystems/xip.txt. Hmm. I don't know. The code and discussions about it looked very big-iron DSCC specific but now on second pass it was meant to more generic. If I can learn this infrastructure then maybe this will work. So I'm supposed to create a function in the target fs that gets plugged into get_xip_page(). Then I call that function to create an proper XIP'ed page in my mmap() and fread() calls. I could use the first arg of get_xip_page() to pass in the start address of the cramfs volume and the second the offset of the page in the file I want to map. Is that about right? This is a lot more overhead than the current XIP Linear CRAMFS patches but it would allow me choose a page-by-page compression/XIP scheme rather than the file-by-file compression/XIP currently used in cramfs. Hmm. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org