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Date: Sat, 28 Jun 2008 20:39:24 +0100
From: Thiemo Seufer <ths@networkno.de>
Subject: Re: [Qemu-devel] MIPS emulation
Message-ID: <20080628193924.GE15737@networkno.de>
References: <200806271350.40937.luke@dashjr.org>
	<200806280901.11619.luke@dashjr.org>
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To: Luke -Jr <luke@dashjr.org>
Cc: qemu-devel@nongnu.org

Luke -Jr wrote:
> On Friday 27 June 2008, Luke -Jr wrote:
> > Is it possible to just emulate a MIPS CPU without any kind of ELF
> > loader/BIOS/boot process, ideally letting me watch/debug the instruction
> > flow and registers?
>
> In particular, I get this log output when I try to boot a flash image:
>=20
> cpu_mips_handle_mmu_fault pc bfc00000 ad bfc00000 rw 2 mmu_idx 0 smmu 1
> cpu_mips_handle_mmu_fault address=3Dbfc00000 ret 0 physical 1fc00000 prot=
 3
> do_raise_exception_err: 15 0
> do_interrupt enter: PC bfc00000 EPC 00000000 instruction bus error except=
ion
> do_interrupt: PC bfc00380 EPC bfc00000 cause 6
>     S 00400006 C 00000418 A 00000000 D 00000000
> do_raise_exception_err: 15 0
> do_interrupt enter: PC bfc00380 EPC bfc00000 instruction bus error except=
ion
> do_interrupt: PC bfc00380 EPC bfc00000 cause 6
>     S 00400006 C 00000418 A 00000000 D 00000000

An "instruction bus error" means Qemu wasn't able to fetch an instruction
=66rom address 0xbfc00000, which should correspond to the very begin of
your flash image. This looks like your Qemu build is broken for some
reason. Did you build with gcc4, per chance?


Thiemo