kernel since 5.6 do not boot anymore on Apple PowerBook

[Christophe Leroy]

Hello Giuseppe,

Le 24/08/2020 à 22:48, Giuseppe Sacco a écrit :
> Hello Christophe,
>
> Il giorno lun, 24/08/2020 alle 07.17 +0200, Christophe Leroy ha
> scritto:
>> Hello Giuseppe,
> [...]
>> The Oopses in the video are fixed in 5.9-rc2, see my response to your
>> other mail.
>
> Right, I just updated from git and rebuilt the kernel whith
> CONFIG_VMAP_STACK not set and the machine boots correctly.
>
>> So now we know that your kernel doesn't boot when CONFIG_VMAP_STACK 
>> is set.
>> Can you remind the exact problem ?
>
> latest kernel with CONFIG_VMAP_STACK set stops after writing:
> pmac32_cpufreq: registering PowerMac CPU frequency driver
> pmac32_cpufreq: Low: 667 MHz, High: 867 Mhz, Boot: 667 MHz
>
>> One common problem with CONFIG_VMAP_STACK is when some drivers are
>> invalidly using buffers in stack for DMA.
>>
>> Couldn't try with CONFIG_DEBUG_VIRTUAL (without CONFIG_VMAP_STACK) and
>> see if it triggers some warnings ?
>
> I've just tried: it boots without any special warning. What should I
> look for? This is an excerpt of dmesg output about the line it would
> otherwise stop:

If there is no warning, then the issue is something else, bad luck.

Could you increase the loglevel and try again both with and without 
VMAP_STACK ? Maybe we'll get more information on where it stops.

Christophe

>
> [...]
> [ 6.566984] PowerMac i2c bus pmu 2 registered
> [ 6.574879] PowerMac i2c bus pmu 1 registered
> [ 6.582634] PowerMac i2c bus mac-io 0 registered
> [ 6.590323] i2c i2c-2: No i2c address for 
> /pci at f2000000/mac-io at 17/i2c at 18000/i2c-modem
> [ 6.598290] PowerMac i2c bus uni-n 1 registered
> [ 6.606196] i2c i2c-3: i2c-powermac: modalias failure on 
> /uni-n at f8000000/i2c at f8001000/cereal at 1c0
> [ 6.614320] PowerMac i2c bus uni-n 0 registered
> [ 6.622501] pmac32_cpufreq: Registering PowerMac CPU frequency driver
> [ 6.630580] pmac32_cpufreq: Low: 667 Mhz, High: 867 Mhz, Boot: 667 Mhz
> [ 6.639518] ledtrig-cpu: registered to indicate activity on CPUs
> [ 6.647894] NET: Registered protocol family 10
> [ 6.656492] Segment Routing with IPv6
> [ 6.664490] mip6: Mobile IPv6
> [ 6.672337] NET: Registered protocol family 17
> [ 6.680213] mpls_gso: MPLS GSO support
> [...]
>
> Bye,
> Giuseppe
>