From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753368Ab1LCIxy (ORCPT ); Sat, 3 Dec 2011 03:53:54 -0500 Received: from mail-ee0-f46.google.com ([74.125.83.46]:37321 "EHLO mail-ee0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752737Ab1LCIxw (ORCPT ); Sat, 3 Dec 2011 03:53:52 -0500 Message-ID: <4ED9E228.8090109@gmail.com> Date: Sat, 03 Dec 2011 09:47:36 +0100 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: Kees Cook CC: Chen Gong , linux-kernel@vger.kernel.org, Tony Luck , Randy Dunlap , Arnd Bergmann , Greg Kroah-Hartman , Andrew Morton Subject: Re: [PATCH v2] ramoops: use pstore interface References: <20111128200951.GA3492@www.outflux.net> <4ED4647D.4060305@linux.intel.com> <4ED75765.5020002@gmail.com> <4ED83AB8.3000000@linux.intel.com> <4ED88A40.6000808@gmail.com> In-Reply-To: Content-Type: text/plain; charset=GB2312 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Il 02/12/2011 20:19, Kees Cook ha scritto: > On Fri, Dec 2, 2011 at 12:20 AM, Marco Stornelli > wrote: >> Il 02/12/2011 03:40, Chen Gong ha scritto: >> >>> ÓÚ 2011/12/1 18:31, Marco Stornelli дµÀ: >>>> >>>> Il 29/11/2011 18:24, Kees Cook ha scritto: >>>>> >>>>> On Mon, Nov 28, 2011 at 8:50 PM, Chen Gong >>>>> wrote: >>>>>> >>>>>> ÓÚ 2011/11/29 4:09, Kees Cook дµÀ: >>>>>>> >>>>>>> >>>>>>> Instead of using /dev/mem directly, use the common pstore >>>>>>> infrastructure >>>>>>> to handle Oops gathering and extraction. >>>>>>> >>>>>>> Signed-off-by: Kees Cook >>>>>>> --- >>>>>>> This depends on the pstore changes waiting for -next in: >>>>>>> >>>>>>> >>>>>>> http://git.kernel.org/?p=linux/kernel/git/aegl/linux.git;a=shortlog;h=refs/heads/next >>>>>>> >>>>>>> >>>>>>> --- >>>>>>> Documentation/ramoops.txt | 8 +- >>>>>>> drivers/char/Kconfig | 1 + >>>>>>> drivers/char/ramoops.c | 206 >>>>>>> ++++++++++++++++++++++++++++++++++----------- >>>>>>> 3 files changed, 160 insertions(+), 55 deletions(-) >>>>>>> >>>>>>> diff --git a/Documentation/ramoops.txt b/Documentation/ramoops.txt >>>>>>> index 8fb1ba7..a0b9d8e 100644 >>>>>>> --- a/Documentation/ramoops.txt >>>>>>> +++ b/Documentation/ramoops.txt >>>>>>> @@ -3,7 +3,7 @@ Ramoops oops/panic logger >>>>>>> >>>>>>> Sergiu Iordache >>>>>>> >>>>>>> -Updated: 8 August 2011 >>>>>>> +Updated: 17 November 2011 >>>>>>> >>>>>>> 0. Introduction >>>>>>> >>>>>>> @@ -71,6 +71,6 @@ timestamp and a new line. The dump then continues >>>>>>> with >>>>>>> the actual data. >>>>>>> >>>>>>> 4. Reading the data >>>>>>> >>>>>>> -The dump data can be read from memory (through /dev/mem or other >>>>>>> means). >>>>>>> -Getting the module parameters, which are needed in order to parse the >>>>>>> data, can >>>>>>> -be done through /sys/module/ramoops/parameters/* . >>>>>>> +The dump data can be read from the pstore filesystem. The format for >>>>>>> these >>>>>>> +files is "dmesg-ramoops-N", where N is the record number in >>>>>>> memory. To >>>>>>> delete >>>>>>> +a stored record from RAM, simply unlink the respective pstore file. >>>>>> >>>>>> >>>>>> I think the definition of "mem_address" in the doc is not very >>>>>> clear. It is >>>>>> not a normal memory instead of a persistent RAM. I suggest adding more >>>>>> descriptions. >>>>>> It's better if there is a real example. >>>>> >>>>> Okay. I'm not sure it's in the scope of this patch, but I can try. >>>>> >>>>> Marco, do you have suggestions for how this could be enhanced? >>>> >>>> I don't know actually. It's not mandatory use a persistent memory. A >>>> simple >>>> piece of reserved RAM is ok. Obviously it will work only over reboot >>>> and not >>>> over power down. I define mem_address as a generic piece of reserved >>>> memory. >>> >>> Anyway, we need a pratical exmaple to instruct us how to use this diver. >> >> For example we can use the mem parameter to reserve memory and use it as >> ramoops buffer, very simple. > > I tried both "mem" and "memmap": > > mem=0x3f000000 ramoops.mem_address=0x3f000000 ramoops.mem_size=0x40000 > ramoops.record_size=0x10000 > > memmap=256K$0x3f000000 ramoops.mem_address=0x3f000000 > ramoops.mem_size=0x40000 ramoops.record_size=0x10000 > > Neither works for me (I end up triggering a panic via BUG in kfree). I > wonder if it's some bad interaction between the cmdline and the memory > tables? When I boot with mem=0x3f000000 and without ramoops, I see in > /proc/iomem: > > 00100000-3effffff : System RAM > 01000000-0137c35f : Kernel code > 0137c360-0151e85f : Kernel data > 01591000-01627fff : Kernel bss > 3f000000-3fffcfff : RAM buffer > > It seems like the system isn't ignoring the region? What's the right > way to do this? > > -Kees > I don't know, however in that situation it's normal to have a crash, if you use the RAM buffer region, you should see "reserved" in iomem. It can be an other kind of problem. Marco