kernel since 5.6 do not boot anymore on Apple PowerBook

[Christophe Leroy]

Hi Giuseppe,

Le 08/07/2020 à 09:59, Giuseppe Sacco a écrit :
> Hello Cristophe,
> 
> Il giorno mar, 07/07/2020 alle 17.34 +0200, Giuseppe Sacco ha scritto:
>> Il giorno mar, 07/07/2020 alle 16.52 +0200, Christophe Leroy ha
>> scritto:
>>> Le 07/07/2020 à 16:03, Giuseppe Sacco a écrit :
>>>> Hello Cristophe,
>>>>
>>>>> Can you tell which defconfig you use or provide your .config
>>>>
>>>> You may get the standard one from debian or a reduced one that I
>>>> made on purpose. The latter is here:
>>>> https://eppesuigoccas.homedns.org/~giuseppe/config-5.4.50.gz
>>>>
>>>>   (boot)
>>>> https://eppesuigoccas.homedns.org/~giuseppe/config-5.6.19.gz
>>>>
>>>>   (no boot)
>>>
>>> Thanks
>>>
>>> Can you provide the complete output when it works, so that I can
>>> see
>>> what is after the place it stops when it fails.
>>
>> Here it is:
>> https://eppesuigoccas.homedns.org/~giuseppe/dmesg-5.4.40-minimo.gz
>>
>>
>>> And can you try without CONFIG_VMAP_STACK on 5.6.19
>>
>> Sure, I'll let you know.
> 
> No, this change did not make the kernel boot. I only changed the option
> you proposed:
> 
> $ grep VMAP .config
> CONFIG_HAVE_ARCH_VMAP_STACK=y
> # CONFIG_VMAP_STACK is not set
> 

Ok, at least it is not that. I wanted to be sure because this is a huge 
change added recently that is selected by default.

I tried on QEMU with your config, it boots properly.

So I think the only way now will be to bisect. Hope you were able to 
setup a cross compiler on a speedy machine.

Christophe