Re: [Qemu-block] [PATCH v2 5/6] qemu-iotests: Test setting WCE with qdev

[Kevin Wolf]

Am 02.07.2016 um 18:15 hat Max Reitz geschrieben:
> On 30.06.2016 16:13, Kevin Wolf wrote:
> > +        echo "info block" \
> > +            | run_qemu -drive "$drive,cache=$cache" \
> > +                       -device "ide-hd,drive=none0$wce" \
> > +            | grep -e "Testing" -e "Cache mode"
> 
> Something interesting: If you'd specify the drive through a node name,
> then the BDS tree has two BBs, one implicitly created with -drive (this
> one is named (automatically) and owned by the monitor) and an anonymous
> one for the device. If the device then overrides the cache mode, this
> will not be reflected in the monitor-owned BB. "info block" (and
> query-block) use the monitor BBs, however, so they'll report the BB on
> top of the BDS tree in question to be in whatever mode has been
> specified in -drive, whereas the mode the device uses for accessing that
> BDS tree actually has nothing to do with that.
> 
> So the user has no way of inquiring the cache mode used by the device,
> and they actually get presented misleading information.

Yes, I know. Originally I wanted to add test cases that use node-name,
but then it occurred to me that this would be pretty pointless.

I'm not sure yet what the conclusion is. Change query-block to include
anonymous BBs that are owned by devices? A new query command? Add the
information to info qtree and whatever the QMP version of it is (if it
even exists)?

Kevin

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