Re: [Qemu-devel] [PATCH 01/13] PPC: Allow Rc bit to be set on mtspr

[David Gibson]

On Fri, Oct 23, 2015 at 02:56:26PM +0100, Mark Cave-Ayland wrote:
> From: Alexander Graf <address@hidden>
> 
> According to the ISA setting the Rc bit on mtspr is undefined behavior.
> Real 750 hardware simply ignores the bit and doesn't touch cr0 though.
> 
> Unfortunately, Mac OS 9 relies on this fact and executes a few mtspr
> instructions (to set XER for example) with Rc set.
> 
> So let's handle the bit the same way hardware does and ignore it.
> 
> Signed-off-by: Alexander Graf <address@hidden>
> Signed-off-by: Mark Cave-Ayland <address@hidden>

Reviewed-by: David Gibson <address@hidden>

> ---
>  target-ppc/translate.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/target-ppc/translate.c b/target-ppc/translate.c
> index c2bc1a7..d1f0f13 100644
> --- a/target-ppc/translate.c
> +++ b/target-ppc/translate.c
> @@ -9884,7 +9884,7 @@ GEN_HANDLER(mtcrf, 0x1F, 0x10, 0x04, 0x00000801, 
> PPC_MISC),
>  GEN_HANDLER(mtmsrd, 0x1F, 0x12, 0x05, 0x001EF801, PPC_64B),
>  #endif
>  GEN_HANDLER(mtmsr, 0x1F, 0x12, 0x04, 0x001FF801, PPC_MISC),
> -GEN_HANDLER(mtspr, 0x1F, 0x13, 0x0E, 0x00000001, PPC_MISC),
> +GEN_HANDLER(mtspr, 0x1F, 0x13, 0x0E, 0x00000000, PPC_MISC),
>  GEN_HANDLER(dcbf, 0x1F, 0x16, 0x02, 0x03C00001, PPC_CACHE),
>  GEN_HANDLER(dcbi, 0x1F, 0x16, 0x0E, 0x03E00001, PPC_CACHE),
>  GEN_HANDLER(dcbst, 0x1F, 0x16, 0x01, 0x03E00001, PPC_CACHE),

-- 
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_!
http://www.ozlabs.org/~dgibson

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