Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 9 Sep 2002 07:09:07 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 9 Sep 2002 07:09:07 -0400 Received: from pc-80-195-35-48-ed.blueyonder.co.uk ([80.195.35.48]:43137 "EHLO sisko.scot.redhat.com") by vger.kernel.org with ESMTP id ; Mon, 9 Sep 2002 07:09:06 -0400 Date: Mon, 9 Sep 2002 12:13:48 +0100 From: "Stephen C. Tweedie" To: David Woodhouse Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Stephen Tweedie Subject: Re: [RFC] On paging of kernel VM. Message-ID: <20020909121348.B4855@redhat.com> References: <2653.1031563253@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: <2653.1031563253@redhat.com>; from dwmw2@infradead.org on Mon, Sep 09, 2002 at 10:20:53AM +0100 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1007 Lines: 25 Hi, On Mon, Sep 09, 2002 at 10:20:53AM +0100, David Woodhouse wrote: > I think I'd like to introduce 'real' VMAs into kernel space, so that areas > in the vmalloc range can have 'real' vm_ops and more to the point a real > nopage function. The alternative is a kmap-style mechanism for temporarily mapping pages beyond physical memory on demand. That would avoid the space limits we have on vmalloc etc; there's only a few tens of MB of address space we can use for mmap tricks in kernel space, so persistent maps are seriously constrained if you've got a lot of flash you want to map. And with a kmap interface, your locking problems are much simpler --- you can trap accesses at source and you don't have to go hunting ptes to invalidate. Cheers, Stephen - 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/