linux-kernel - Re: [PATCH 09/20] of/fdt: create common debugfs

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Message-ID: <53424E14.9080100@monstr.eu>
Date:	Mon, 07 Apr 2014 09:04:52 +0200
From:	Michal Simek <monstr@...str.eu>
To:	Rob Herring <robherring2@...il.com>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Grant Likely <grant.likely@...aro.org>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@...ba.org>,
	linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>
Subject: Re: [PATCH 09/20] of/fdt: create common debugfs

On 04/07/2014 02:42 AM, Rob Herring wrote:
> On Fri, Apr 4, 2014 at 9:11 AM, Michal Simek <monstr@...str.eu> wrote:
>> On 04/04/2014 03:32 PM, Rob Herring wrote:
>>> On Fri, Apr 4, 2014 at 8:22 AM, Michal Simek <monstr@...str.eu> wrote:
>>>> On 04/04/2014 03:00 PM, Rob Herring wrote:
>>>>> On Fri, Apr 4, 2014 at 7:16 AM, Michal Simek <monstr@...str.eu> wrote:
>>>>>> On 04/04/2014 12:16 AM, Rob Herring wrote:
>>>>>>> From: Rob Herring <robh@...nel.org>
>>>>>>>
>>>>>>> Both powerpc and microblaze have the same FDT blob in debugfs feature.
>>>>>>> Move this to common location and remove the powerpc and microblaze
>>>>>>> implementations. This feature could become more useful when FDT
>>>>>>> overlay support is added.
>>>>>
>>>>> [snip]
>>>
>>>> Anyway I am testing it for microblaze and getting problem
>>>> caused by this patch:
>>>> commit 3d2ee8571ac0580d49c3f41fa28336289934900a
>>>> Author: Rob Herring <robh@...nel.org>
>>>> Date:   Wed Apr 2 15:10:14 2014 -0500
>>>>
>>>>     of/fdt: Convert FDT functions to use libfdt
>>>>
>>>> And reason is that in unflatten_dt_node()
>>>>
>>>> pathp = fdt_get_name(blob, *poffset, &l);
>>>>
>>>> is returning NULL
>>>> and here
>>>>         /* version 0x10 has a more compact unit name here instead of the full
>>>>          * path. we accumulate the full path size using "fpsize", we'll rebuild
>>>>          * it later. We detect this because the first character of the name is
>>>>          * not '/'.
>>>>          */
>>>>         if ((*pathp) != '/') {
>>>>
>>>> code is trying to read it which is causing this kernel bug:
>>>> Oops: kernel access of bad area, sig: 11
>>>>
>>>> It means fdt_next_node(is doing something wrong)
>>>>
>>>> Any easy way how to debug it?
>>>
>>> I didn't think fdt_get_path should fail. Can you add a print of
>>> *poffset and pathp values.
> 
> I think I've fixed this now and updated the branch. Please test again
> when you have a chance.

yep. The updated branch works for Microblaze.

Thanks,
Michal


-- 
Michal Simek, Ing. (M.Eng), OpenPGP -> KeyID: FE3D1F91
w: www.monstr.eu p: +42-0-721842854
Maintainer of Linux kernel - Microblaze cpu - http://www.monstr.eu/fdt/
Maintainer of Linux kernel - Xilinx Zynq ARM architecture
Microblaze U-BOOT custodian and responsible for u-boot arm zynq platform



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