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Re: [Qemu-devel] [Bug] [Patch] MIPS code fails at branch instruction
From: |
Thiemo Seufer |
Subject: |
Re: [Qemu-devel] [Bug] [Patch] MIPS code fails at branch instruction |
Date: |
Mon, 19 Mar 2007 22:34:49 +0000 |
User-agent: |
Mutt/1.5.13 (2006-08-11) |
Thiemo Seufer wrote:
[snip]
> > Patched QEMU HEAD (see appended patch file):
> >
> > * The code works in a well defined way. An optional message in the log file
> > will show the faulty statement. It won't amount to a DoS because it
> > is disabled by default.
>
> Sorry, but I missed the "well defined". What does the jump in the branch
> delay slot exactly _do_ now? Where does the PC point to when it was a
> conditional branch which wasn't taken?
I committed something which cover the rest of your patch, and throws
now a RI exception for branch-in-branch-delay-slot.
For the AR7 case, could you
- add AR7 as a CPU type
- handle the interesting cases for AR7 only, after verifying the
cornercase behaviour of qemu and real hardware is consistent.
The cornercases which come to mind:
- conditional vs. unconditional branches
- the various condition types
- taken vs. non-taken branches
- linked vs. non-linked branches
- likely vs. non-likely branches
- the side effects of j / jal in the delayslot
- the value of PC/ra (if it changes)
I don't ask for an exhaustive analysis, I just want to see the cases of
interest covered, so we can be reasonably sure the qemu results will be
useful for other AR7 users as well.
Thiemo
- [Qemu-devel] [Bug] MIPS code fails at branch instruction, Stefan Weil, 2007/03/16
- Re: [Qemu-devel] [Bug] MIPS code fails at branch instruction, Thiemo Seufer, 2007/03/16
- Re: [Qemu-devel] [Bug] MIPS code fails at branch instruction, Stefan Weil, 2007/03/17
- Re: [Qemu-devel] [Bug] MIPS code fails at branch instruction, Thiemo Seufer, 2007/03/17
- Re: [Qemu-devel] [Bug] MIPS code fails at branch instruction, Stefan Weil, 2007/03/17
- Re: [Qemu-devel] [Bug] MIPS code fails at branch instruction, Paul Brook, 2007/03/17
- Re: [Qemu-devel] [Bug] [Patch] MIPS code fails at branch instruction, Stefan Weil, 2007/03/19
- Re: [Qemu-devel] [Bug] [Patch] MIPS code fails at branch instruction, Thiemo Seufer, 2007/03/19
- Re: [Qemu-devel] [Bug] [Patch] MIPS code fails at branch instruction,
Thiemo Seufer <=
- Re: [Qemu-devel] [Bug] [Patch] MIPS code fails at branch instruction, Alexander Voropay, 2007/03/20
- Re: [Qemu-devel] [Bug] [Patch] MIPS code fails at branch instruction, Thiemo Seufer, 2007/03/20
- Re: [Qemu-devel] [Bug] [Patch] MIPS code fails at branch instruction, Stefan Weil, 2007/03/20
- Re: [Qemu-devel] [Bug] [Patch] MIPS code fails at branch instruction, Thiemo Seufer, 2007/03/24
- Re: [Qemu-devel] [Bug] [Patch] MIPS code fails at branch instruction, Aurelien Jarno, 2007/03/24
- Re: [Qemu-devel] [Bug] [Patch] MIPS code fails at branch instruction, Stuart Brady, 2007/03/25
- Re: [Qemu-devel] [Bug] [Patch] MIPS code fails at branch instruction, Thiemo Seufer, 2007/03/25