From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-la0-f53.google.com (mail-la0-f53.google.com [209.85.215.53]) by kanga.kvack.org (Postfix) with ESMTP id 0F0A56B0032 for ; Fri, 5 Dec 2014 12:53:03 -0500 (EST) Received: by mail-la0-f53.google.com with SMTP id gm9so1070589lab.26 for ; Fri, 05 Dec 2014 09:53:02 -0800 (PST) Received: from mail-lb0-f169.google.com (mail-lb0-f169.google.com. [209.85.217.169]) by mx.google.com with ESMTPS id ku5si29623903lac.26.2014.12.05.09.53.01 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Fri, 05 Dec 2014 09:53:01 -0800 (PST) Received: by mail-lb0-f169.google.com with SMTP id p9so945087lbv.14 for ; Fri, 05 Dec 2014 09:53:01 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <20141205172701.GW11285@n2100.arm.linux.org.uk> References: <35FD53F367049845BC99AC72306C23D103D6DB491609@CNBJMBX05.corpusers.net> <20140915113325.GD12361@n2100.arm.linux.org.uk> <20141204120305.GC17783@e104818-lin.cambridge.arm.com> <20141205120506.GH1630@arm.com> <20141205170745.GA31222@e104818-lin.cambridge.arm.com> <20141205172701.GW11285@n2100.arm.linux.org.uk> From: Peter Maydell Date: Fri, 5 Dec 2014 17:52:41 +0000 Message-ID: Subject: Re: [RFC v2] arm:extend the reserved mrmory for initrd to be page aligned Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Russell King - ARM Linux Cc: Catalin Marinas , Peter Maydell , "Wang, Yalin" , "linux-arm-msm@vger.kernel.org" , Will Deacon , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "linux-arm-kernel@lists.infradead.org" On 5 December 2014 at 17:27, Russell King - ARM Linux wrote: > On Fri, Dec 05, 2014 at 05:07:45PM +0000, Catalin Marinas wrote: >> On Fri, Dec 05, 2014 at 12:05:06PM +0000, Will Deacon wrote: >> > Care to submit this as a proper patch? We should at least fix Peter's issue >> > before doing things like extending headers, which won't work for older >> > kernels anyway. >> >> Quick fix is the revert of the whole patch, together with removing >> PAGE_ALIGN(end) in poison_init_mem() on arm32. If Russell is ok with >> this patch, we can take it via the arm64 tree, otherwise I'll send you a >> partial revert only for the arm64 part. > > Not really. Let's look at the history. > > For years, we've been poisoning memory, page aligning the end pointer. > This has never been an issue. Depends what you mean by "never been an issue". I had to change QEMU (commit 98ed805c, January 2013) for 32-bit ARM back when the kernel started trashing the tail end of the page after the initrd with the poisoning, to 4K-align the dtb so it didn't share a page with the initrd-tail. That nobody else complained suggests that most bootloaders don't in practice overlap the two, though (ie that QEMU is an outlier in how it chooses to arrange things in memory). I should probably have reported the breakage at the time, but I took the pragmatic (lazy?) approach of just changing our bootloader code. thanks -- PMM -- 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