Kernel 5.10-rc4 doesn't boot

[Christophe Leroy]

Le 29/11/2020 à 02:33, Stan Johnson a écrit :
> 
>>
>>
>> On 11/25/20 5:52 AM, Elimar Riesebieter wrote:
>>>
>>> * John Paul Adrian Glaubitz <glaubitz at physik.fu-berlin.de>[2020-11-25
>>> 13:04 +0100]:
>>>>
>>>> On 11/25/20 12:40 PM, Elimar Riesebieter wrote:
>>>>>
>>>>> I tried to boot linux-image-5.10.0-rc4-powerpc on my PowerBook5,8.
>>>>> It seems the ramdisk isn't loaded as ist stocks at the white
>>>>> firmware boot. A custom build fails as well. I have no idea how to
>>>>> debug that. I am booting via yaboot.
>>>>
>>>> FWIW, if you think the initrd isn't being loaded, you may have run
>>>> into a limitation with Yaboot. You have to keep in mind that Yaboot
>>>> isn't being actively maintained anymore, at least not as it used to
>>>> be. So in case of an incompatible change on the kernel side, you may
>>>> run into such problems with the bootloader. You could try switching
>>>> to GRUB.
>>>
>>> What is the preferred way to switch to grub2? Elimar
>>
>>
>> HelloElimar,
>>
>> I can confirm that Linux 5.10.0-rc5 also does not work on a PowerBook
>> Lombard, hanging at the "found display ... opening ..." screen after
>> loading the initrd.img file.
>>
>> The 5.10.0-rc5 initrd.img can be used with an older 5.8.4 kernel;
>> however, the 5.8.4 initrd.img does not work with the 5.10.0-rc5
>> kernel, so the problem appears to be with the 5.10.0-rc5 kernel.
>>
>> ...
>>
>> -Stan Johnson
>>
> 
> The Wallstreet also won't boot any 5.10.0-rc* kernel (it hangs at the
> BootX screen).  The last v5.9 mainline kernel (v5.9.11) boots on both
> the Wallstreet and Lombard (so it's likely the same problem).
> 
> I saw during one of the boots that PPC 601 support has been removed; I
> thought that there was still an effort not to do that (but that's a
> separate issue).

PPC 601 has been broken for several kernels, and nobody noticed so we concluded it was unused with 
new kernels and finally removed it completely in order to kick out all 601 particularities that were 
a nightmare.

> 
> A git bisect going from v5.9 to v5.10.0-rc1 resulted in the following,
> after about 13 kernels:
> 
> -----
> 69a1593abdbcf03a76367320d929a8ae7a5e3d71 is the first bad commit
> -----
> 
> I'm cc'ing Christophe Leroy, since I don't know what to do next.

Try following commit: 
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=01776f070ffcbf336be3bf1672bd3c589548d6c4

Christophe