[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Qemu-devel] [Bug] qemu-system-ppc: "invalid/unsupported opcode" dur

From: Aurelien Jarno
Subject: Re: [Qemu-devel] [Bug] qemu-system-ppc: "invalid/unsupported opcode" during debug session
Date: Sun, 28 Feb 2010 16:00:58 +0100
User-agent: Mutt/1.5.18 (2008-05-17)

On Sun, Feb 28, 2010 at 02:02:33PM +0000, Paul Brook wrote:
> > > invalid/unsupported opcode: 00 - 00 - 00 (00000000) 4800fa44 1
> > 
> > I have fixed that in HEAD by stopping the translation just after a trap,
> > as the instructions might never be executed.
> > 
> > It is not a full fix, as the OS can actually use any instruction that
> > always generate a trap (even a memory access) as an instruction barrier
> > to make sure the following instructions are never executed. This
> > actually affects all targets, but is unlikely to happen.
> > 
> > One solution for that would be to only generate an exception for an
> > unsupported instruction when it is the first instruction of a TB, and
> > otherwise just end the translation before this instruction.
> By my reading the code is correct. We end up calling gen_invalid which output 
> code to raise an invalid instruction exception. If earlier code faults at 
> runtime then that code is never executed, and everything is happy.

You are correct, I have read the code too quickly. So ignore what I said

> The real bug is that we have debugging printfs enabled by default.

Agreed, I'll fix that.

Aurelien Jarno                          GPG: 1024D/F1BCDB73
address@hidden                 http://www.aurel32.net

reply via email to

[Prev in Thread] Current Thread [Next in Thread]