Kernel 4.7: PAGE_GUARDED and _PAGE_NO_CACHE

[Christian Zigotzky]

Hi All,

The commit powerpc-4.7-2 [2] was released yesterday.

There is a conflict in my local kernel git directory if I use git pull 
because I have reverted the commit powerpc-4.7-1. [1]

The commit powerpc-4.7-2 [2] needs the commit powerpc-4.7-1. [1]

I created a new local kernel git directory for the RC2 with:

git clone 
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 
linux-git-without-powerpc-commits

After that I reverted the two commits:

powerpc-4.7-2 [2]:

git revert 5306d766f15e72bc79c61d88f77e5a6b1fcc0e68 -m 1

powerpc-4.7-1 [1]:

git revert c04a5880299eab3da8c10547db96ea9cdffd44a6 -m 1

Afterwards I successfully tested our latest Nemo patch 4.7-1 [3] with 
the following commands:

cp -R linux-git-without-powerpc-commits linux-4.7

patch -p0 < nemo_4.7-1.patch

I tried to solve the boot issue last week. I modified the code a lot and 
I replaced some files. Unfortunately without any success. The RC1 
without the commit powerpc-4.7-1 [1] boots and works fantastic. I don't 
have any ideas anymore. Please help me to solve the boot problems.

Thanks in advance,

Christian

[1] 
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=c04a5880299eab3da8c10547db96ea9cdffd44a6
[2] 
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=5306d766f15e72bc79c61d88f77e5a6b1fcc0e68
[3] http://www.xenosoft.de/nemo_4.7-1.patch

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

On 28 May 2016 at 6:53 PM, 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.
>
> The difficult bit that usually breaks on kernel upgrades is not the WIMG settings, but the PCI probing routine.  The SB600 doesn't follow normal PCIe address decoding rules, as in its original use as an AMD south bridge it was designed to appear as if it were integrated into the north bridge.
>
> --
> Adrian
>