On 04/14/2016 01:57 PM, Russell King - ARM Linux wrote:
> On Thu, Apr 14, 2016 at 05:43:30PM +0200, Alexander Aring wrote:
>> Hi,
>>
>> since commit 25362dc ("ARM: 8501/1: mm: flip priority of CONFIG_DEBUG_RODATA")
>> which enables for (in my case) am335x CONFIG_DEBUG_RODATA by default, I notice
>> that my beaglebone white doesn't boot anymore when this config is enabled.
>>
>> I boot current linus/master via barebox v2016.04.0 with zImage format.
>> The following message will be printed:
>>
>> Error: unrecognized/unsupported machine ID (r1 = 0x00000ee0).
>>
>> When I turn off CONFIG_DEBUG_RODATA it boots fine again.
>>
>> Does somebody experienced similar issues or somebody know maybe what
>> happens here?
>
> It will have the effect of bloating the size of the kernel image,
> which means if you have a dodgy uboot setup which loads the DTB
> too close to the kernel image, the kernel will overwrite the DTB
> while decompressing, which then means that the kernel can't find
> the DTB anymore.
Yep - i have been bitten by this with multi_v7_defconfig more than I
like to..
https://github.com/nmenon/kernel-test-logs/blob/next-20160414/multi_v7_defconfig/beaglebone.txt
if you'd like to compare the addresses used.
> So, it's probably a uboot problem rather than a kernel problem.
> The fix is to adjust the uboot variables to arrange for the DTB
> to be placed further from the kernel image.
This is probably barebox[1] -> u-boot is a little smart and reorganizes
zImage dtb ramdisk etc based on fdt_high and few other variables I cant
seem to remember now.
> Sorry, but I forget the details as to what uboot variables need
> changing, I'm not a uboot hacker. I adjust things on my platforms
> so stuff works again and then forget it (otherwise I'd need to
> remember settings for soo many different platforms...)
>
[1]http://git.pengutronix.de/?p=barebox.git
--
Regards,
Nishanth Menon
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