Re: [libvirt] [PATCH 09/14] Fix check for whether a suspend target is supported
On 11/29/2011 10:10 PM, Daniel P. Berrange wrote:
On Tue, Nov 29, 2011 at 09:33:09AM -0700, Eric Blake wrote:
> On 11/29/2011 08:44 AM, Daniel P. Berrange wrote:
>> From: "Daniel P. Berrange" <berrange(a)redhat.com>
>>
>> hostPMFeatures is a bitmask, but the VIR_NODE_SUSPEND_TARGET
>> constants are from an enum. Thus the code was checking the
>> wrong bit values
>
> Yep - regression introduced in patch 1/14. Maybe you should squash this
> in to that patch, so that bisecting doesn't hit the regression (although
> that would mean patching a different file, since you moved the function
> location in the meantime). Up to you if you want to go to the hassle.
It wasn't a regression actually. This code was still using the
duplicate enum at that point:
enum virHostPMCapability {
VIR_HOST_PM_S3, /* Suspend-to-RAM */
VIR_HOST_PM_S4, /* Suspend-to-Disk */
VIR_HOST_PM_HYBRID_SUSPEND, /* Hybrid-Suspend */
VIR_HOST_PM_LAST
};
So AFAICT, it was broken from the start.
I beg to differ here. It was a bit weird, but definitely not broken.
Since VIR_HOST_PM_S3 etc were linear (0,1,2), a bit-wise OR operation
was carried out like this: *bitmask |= 1U << feature; where feature
was one of the above.
And while checking this, we used to do:
hostPMFeatures & VIR_NODE_SUSPEND_TARGET_HYBRID
where VIR_NODE_SUSPEND_TARGET_HYBRID etc were like 1 << 0, 1 << 1 etc
Thus, this was ugly, but not broken. Otherwise, it would have surely
failed my suspend tests which I ran every time before submitting the
patches :-)
--
Regards,
Srivatsa S. Bhat
IBM Linux Technology Center