Kernel 4.7: PAGE_GUARDED and _PAGE_NO_CACHE

[Christian Zigotzky]

All,

I need an answer because I think Darren's guess is correct. It isn't a 
problem in the pci code. I replaced the file head_64.S that Darren 
mentioned with the one from the kernel 4.6 and it compiled but 
unfortunately it doesn't boot. We know "head_64.S" is one file for the 
early boot phase but I think there are some other files.

I am not a fan of reverting the PowerPC commits but there are some other 
new things in the new kernel e.g. DRM 2.45.0 which are very interesting 
for the Nemo board.

@Julian

What about the issues with the Sam460ex? Have you solved the problem 
with the commit powerpc-4.7-1?

Cheers,

Christian

On 04 June 2016 at 5:25 PM, Christian Zigotzky wrote:
> Which files are responsible for the early boot phase in the commit powerpc-4.7-1? Perhaps the problem is there.
>
> - Christian
>
> Sent from my iPhone
>

On 28 May 2016 at 8:51 PM, Darren Stevens wrote:
> Hello Adrian
>
> On 28/05/2016, Adrian Cox wrote:
>>> From: Christian Zigotzky [mailto:chzigotzky at xenosoft.de]
>>> Sent: 28 May 2016 07:06
>>> Adrian, what is the expected WIMG bit mapping for the Nemo board?
>>>
>> I'm not able to help much here, I'm afraid. I don't have a Nemo board at
>> the moment, and it's been a few years. From memory all the peripherals
>> required standard uncached and guarded mappings on Nemo.
> Before everybody gets too involved, from what I've seen with my tests today
> the kernel is crashing long before it gets to the pci-common code.
>
> I've attached 2 boot logs, one from a 4.4 kernel I've been working on, and
> from a build of the latest git.
>
> You can see from this that the 4.7 kernel hangs right after the booting linux
> via __start(), whereas in the 4.4 there's about 29 lines of output before it
> gets to the Initialised io_base_virt printk in our patch.
>
> The last time we had a hang this early in the boot it turned out to be a
> problem in head_64.S, I think there is something else wrong in the commit
> Christian has identified
>
> I will see if this is something I can fix, but it may need better low level
> knowledge of PPC hardware than I have.
>
> Regards
> Darren