Thread (19 messages) 19 messages, 7 authors, 2022-11-03

Re: Issues with the first PowerPC updates for the kernel 6.1

From: Michael Ellerman <mpe@ellerman.id.au>
Date: 2022-10-17 00:18:44

Olof Johansson [off-list ref] writes:
On Fri, Oct 14, 2022 at 9:11 AM Christian Zigotzky
[off-list ref] wrote:
quoted
make oldconfig has asked because of the CPU family. I choosed GENERIC for my P.A. Semi PWRficient PA6T-1682M. Is this correct? Maybe this is the problem.

config GENERIC_CPU
- bool "Generic (POWER4 and above)"
+ bool "Generic (POWER5 and PowerPC 970 and above)"
  depends on PPC_BOOK3S_64 && !CPU_LITTLE_ENDIAN
  select PPC_64S_HASH_MMU

There isn’t a POWER4 anymore and I used it via CONFIG_GENERIC_CPU=y before.

Before the first PowerPC updates:
CONFIG_GENERIC_CPU=y
# CONFIG_POWER5_CPU is not set

Link: https://github.com/torvalds/linux/blob/master/arch/powerpc/platforms/Kconfig.cputype
I think the mistake here is that there are two GENERIC_CPUs now, and
one of them is the wrong one and overrides settings. I'm surprised
Kconfig didn't balk at it.
We've had two GENERIC_CPUs since 2018:

  a73657ea19ae ("powerpc/64: Add GENERIC_CPU support for little endian")

They're mutually exclusive because of the ENDIAN dependencies.

I don't know if that's supposed to be allowed by Kconfig, but AFAIK it
has been working.
I have a vague memory that PA6T had a little-endian mode, but it was
never used much and I wouldn't expect it to work.
I don't think endian is an issue here. Christian should be getting the
big endian version of GENERIC_CPU.

cheers
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