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Date: Sat, 28 Feb 2009 17:21:34 +0200
Message-ID: <f43fc5580902280721x39ad3c25y1d73b611a73cabf8@mail.gmail.com>
Subject: Re: [Qemu-devel] [PATCH] PPC: Use correct values for 970 interrupts
	and hreset
From: Blue Swirl <blauwirbel@gmail.com>
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To: qemu-devel@nongnu.org
Cc: Alexander Graf <alex@csgraf.de>

On 2/28/09, Alexander Graf <agraf@suse.de> wrote:
> The 970 doesn't set exception prefix values by default. According to
>  the ISA it just jumps to real mode with nip=vector.
>
>  Because of that the current hreset_vector is rendered invalid. Before,
>  it would go to excp_prefix (ROM base) + 0x100 (reset vector) and get
>  into the firmware.
>
>  But with the corrected excp_prefix, we now have to jump to the real
>  entry point, which is at 0xFFFFFFFC.

I don't think this is correct. 970FX uses HIOR to specify the
exception vector base, please see "IBM PowerPC 970FX RISC
Microprocessor", page 273.

>>From OpenBIOS viewpoint both vectors are OK.

>  I can't imagine how any OS that does memory management itself could have
>  possibly worked with the code as it was.

Maybe Qemu uses the 604 exception prefix somewhere.