On 04.07.2016 12:50, Kevin Wolf wrote: > 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)?
Well, since you are basically trying to purge the BB from the user's field of view, it would probably make sense to display all the BB-level information (like the writethrough mode) as part of the device information; that is, probably in info qtree. That information should then probably also include the node name of the root BDS, and the user/management application can find out all about that with query-named-block-nodes (although it'd probably makes sense to add a query-block-node command for a single node). Max
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