semantic: 0.170
other: 0.170
PID: 0.124
device: 0.081
files: 0.076
performance: 0.066
permissions: 0.053
socket: 0.046
vnc: 0.044
network: 0.043
graphic: 0.036
boot: 0.033
debug: 0.031
KVM: 0.028
performance: 0.145
debug: 0.140
semantic: 0.136
files: 0.112
other: 0.105
network: 0.076
PID: 0.059
device: 0.052
boot: 0.046
socket: 0.043
vnc: 0.037
permissions: 0.021
graphic: 0.017
KVM: 0.010

ppc fails to clear MSR_POW when incurring exception

QEMU VERSION: 0.12.4

According to FreeScale's 'Programming Environments Manual for 32-bit Implementations of the PowerPC Architecture' [MPCFPE32B, Rev.3, 9/2005], section 6.5, table 6-7, an interrupt resets MSR_POW to zero but qemu-0.12.4 fails to do so.
Resetting the bit is necessary in order to bring the processor out of power-management since otherwise it goes to sleep right away in the exception handler, i.e., it is impossible to leave PM-mode.



Thomas Monjalon wrote:
> From: till <email address hidden>
>
> According to FreeScale's 'Programming Environments Manual for 32-bit
> Implementations of the PowerPC Architecture' [MPCFPE32B, Rev.3, 9/2005],
> section 6.5, table 6-7, an interrupt resets MSR_POW to zero but qemu-0.12.4
> fails to do so.
> Resetting the bit is necessary in order to bring the processor out of power
> management since otherwise it goes to sleep right away in the exception
> handler, i.e., it is impossible to leave PM-mode.
>   

This doesn't look right. POW shouldn't even get stored in SRR1. Could
you please redo the patch and make sure that mtmsr masks out MSR_POW?


Alex


I'm afraid I don't understand. My the problem and fix doesn't address mtmsr at all.
It just makes sure MSR_POW is cleared in MSR when an exception occurs.

Do you mean MSR_POW should masked from MSR before saving it to SRR1?
That's already taken care of (target-ppc/helper.c:2074 [qemu-0.12.4]).

As far as I can see, this problem has been fixed by this commit here:
http://git.qemu.org/?p=qemu.git;a=commitdiff;h=41557447d30eeb944e4
... so I'm setting the status to "Fix released" now.