Subject: Re: [PATCH 29/38] powerpc: Move 32-bit probe() machine to later in the boot process

From: Benjamin Herrenschmidt <[email-masked]>
Date: Tue, 28 Jun 2016 22:01:19 +1000

On Tue, 2016-06-28 at 13:42 +0200, Gerhard Pircher wrote:
> The question is, if a compile time option that simply clear ?s
> CPU_FTR_NEED_COHERENT after identify_cpu() would be acceptable. And
> then I still wonder why KVM needs its own similar fix to work on the
> AmigaOne. I specifically had to remove/clear the PTE_M bit
> inarch/powerpc/kvm/book3s_32_mmu_host.c for th

No we could just add something to early_init_devtree that does clear
that bit if it sees the relevant piece of broken HW, it's not the AmigaOne per-se, it's the northbridge right ?

We could also make non-coherent cache a runtime option if we really
wanted, it's just more churn ...

> 206         pteg0 = ((eaddr & 0x0fffffff) >> 22) | (vsid << 7) |
> PTE_V |
> 207                 (primary ? 0 : PTE_SEC);
> 208         pteg1 = hpaddr | PTE_M | PTE_R | PTE_C;
>                              ^^^^^
> 
> > Do we know where the lockups come from btw ? A problem with the
> > northbridge ?
> Yes, it's a problem with the northbridge...as usual. :-(

Marvell ?

Cheers,
Ben.