From mboxrd@z Thu Jan 1 00:00:00 1970 From: marco.stornelli@gmail.com (Marco Stornelli) Date: Sat, 29 Oct 2011 10:39:47 +0200 Subject: [PATCH] ramoops appears geared to not support ARM In-Reply-To: <1319844110-23062-1-git-send-email-bfreed@chromium.org> References: <1319844110-23062-1-git-send-email-bfreed@chromium.org> Message-ID: <4EABBBD3.5030700@gmail.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org (Added linux-arm) Il 29/10/2011 01:21, Bryan Freed ha scritto: > I had some difficulty in getting ramoops to work on our ARM systems. > The driver maps memory with ioremap() which is supposed to map IO memory, > not physical RAM. This happens to work on x86 and apparently some other > architectures, but it does not work on ARM. > Specifically, I see this comment in __arm_ioremap_pfn_caller(): > Don't allow RAM to be mapped - this causes problems with ARMv6+ > > So here is a patch that hacks around the issue using page_is_ram() to > differentiate between the two. > > Am I missing something here? > Is ramoops working on any ARM systems yet, and I am just doing something wrong? > > My ARM platform reserves a section of RAM for use by ramoops, but it is still > mapped along with the rest of main memory. This is so /dev/mem can find it > with xlate_dev_mem_ptr(). > On x86, I see our BIOS reserves the memory so that it is not counted as main > memory, and it is not mapped until ramoops ioremaps it. > > Bryan Freed (1): > ramoops: Add support for ARM systems. > > drivers/char/ramoops.c | 67 +++++++++++++++++++++++++++++++++++++---------- > 1 files changed, 52 insertions(+), 15 deletions(-) > Can some ARM guys give an opinion about that? Thanks. Marco From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754658Ab1J2Ipy (ORCPT ); Sat, 29 Oct 2011 04:45:54 -0400 Received: from mail-ww0-f44.google.com ([74.125.82.44]:56945 "EHLO mail-ww0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751183Ab1J2Ipw (ORCPT ); Sat, 29 Oct 2011 04:45:52 -0400 Message-ID: <4EABBBD3.5030700@gmail.com> Date: Sat, 29 Oct 2011 10:39:47 +0200 From: Marco Stornelli User-Agent: Mozilla/5.0 (X11; U; Linux i686; it; rv:1.9.2.23) Gecko/20110920 SUSE/3.1.15 Thunderbird/3.1.15 MIME-Version: 1.0 To: linux-arm-kernel@lists.infradead.org CC: Bryan Freed , linux-kernel@vger.kernel.org, sergiu@chromium.org, akpm@linux-foundation.org, msb@chromium.org, seiji.aguchi@hds.com Subject: Re: [PATCH] ramoops appears geared to not support ARM References: <1319844110-23062-1-git-send-email-bfreed@chromium.org> In-Reply-To: <1319844110-23062-1-git-send-email-bfreed@chromium.org> Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org (Added linux-arm) Il 29/10/2011 01:21, Bryan Freed ha scritto: > I had some difficulty in getting ramoops to work on our ARM systems. > The driver maps memory with ioremap() which is supposed to map IO memory, > not physical RAM. This happens to work on x86 and apparently some other > architectures, but it does not work on ARM. > Specifically, I see this comment in __arm_ioremap_pfn_caller(): > Don't allow RAM to be mapped - this causes problems with ARMv6+ > > So here is a patch that hacks around the issue using page_is_ram() to > differentiate between the two. > > Am I missing something here? > Is ramoops working on any ARM systems yet, and I am just doing something wrong? > > My ARM platform reserves a section of RAM for use by ramoops, but it is still > mapped along with the rest of main memory. This is so /dev/mem can find it > with xlate_dev_mem_ptr(). > On x86, I see our BIOS reserves the memory so that it is not counted as main > memory, and it is not mapped until ramoops ioremaps it. > > Bryan Freed (1): > ramoops: Add support for ARM systems. > > drivers/char/ramoops.c | 67 +++++++++++++++++++++++++++++++++++++---------- > 1 files changed, 52 insertions(+), 15 deletions(-) > Can some ARM guys give an opinion about that? Thanks. Marco