Re: [Qemu-devel] MIPS emulation

[Luke -Jr]

On Thursday 03 July 2008, Thiemo Seufer wrote:
> Luke -Jr wrote:
> > On Saturday 28 June 2008, Thiemo Seufer wrote:
> > > 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:
> > > >
> > > > cpu_mips_handle_mmu_fault pc bfc00000 ad bfc00000 rw 2 mmu_idx 0 smmu
> > > > 1 cpu_mips_handle_mmu_fault address=bfc00000 ret 0 physical 1fc00000
> > > > prot 3 do_raise_exception_err: 15 0
> > > > do_interrupt enter: PC bfc00000 EPC 00000000 instruction bus error
> > > > exception 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
> > > > exception 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 from 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?
> >
> > Just tried and got this same thing with a vanilla checkout of trunk
> > compiled with GCC 3.4.6...
>
> Well, the -pflash option works well enough for me to execute the first
> instructions of a YAMON or redboot image.

-pflash does appear to do a bit better! Strange that -mtdblock doesn't... 
wouldn't that be the most common interface? :/