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Re: [PATCH qemu v6 1/6] ppc: Start CPU in the default mode which is big-

From: David Gibson
Subject: Re: [PATCH qemu v6 1/6] ppc: Start CPU in the default mode which is big-endian 32bit
Date: Wed, 12 Feb 2020 16:43:04 +1100

On Mon, Feb 03, 2020 at 02:29:38PM +1100, Alexey Kardashevskiy wrote:
> At the moment we enforce 64bit mode on a CPU when reset. This does not
> make difference as SLOF or Linux set the desired mode straight away.
> However if we ever boot something other than these two,
> this might not work as, for example, GRUB expects the default MSR state
> and does not work properly.
> This removes setting MSR_SF from the PPC CPU reset.

Hrm.  This is in the core cpu model so it doesn't just affect pseries,
but powernv (and theoretically others) as well.  Generally the cpu
model should have the bare metal behaviour, and we can override it in
the pseries machine if necessary.

So for a bare metal POWER system, what mode do we start in?  I'm
guessing it probably doesn't matter in practice, since the skiboot
firmware also probably does a mode set on entry, but it'd be nice to
get this right in theory.

> Signed-off-by: Alexey Kardashevskiy <address@hidden>
> ---
>  target/ppc/translate_init.inc.c | 6 ------
>  1 file changed, 6 deletions(-)
> diff --git a/target/ppc/translate_init.inc.c b/target/ppc/translate_init.inc.c
> index 53995f62eab2..f6a676cf55e8 100644
> --- a/target/ppc/translate_init.inc.c
> +++ b/target/ppc/translate_init.inc.c
> @@ -10710,12 +10710,6 @@ static void ppc_cpu_reset(CPUState *s)
>  #endif
>  #endif
> -#if defined(TARGET_PPC64)
> -    if (env->mmu_model & POWERPC_MMU_64) {
> -        msr |= (1ULL << MSR_SF);
> -    }
> -#endif
> -
>      hreg_store_msr(env, msr, 1);
>  #if !defined(CONFIG_USER_ONLY)

David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!

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