On Sep 16 14:41, Kevin Wolf wrote: > Am 14.09.2021 um 22:37 hat Klaus Jensen geschrieben: > > From: Klaus Jensen <k.jen...@samsung.com> > > > > Hi, > > > > This is an attempt at adressing a bunch of issues that have presented > > themselves since we added subsystem support. It's been brewing for a > > while now. > > > > Fundamentally, I've come to the conclusion that modeling namespaces and > > subsystems as "devices" is wrong. They should have been user-creatable > > objects. We've run into multiple issues with wrt. hotplugging due to how > > namespaces hook up to the controller with a bus. The bus-based design > > made a lot of sense when we didn't have subsystem support and it follows > > the design of hw/scsi. But, the problem here is that the bus-based > > design dictates a one parent relationship, and with shared namespaces, > > that is just not true. If the namespaces are considered to have a single > > parent, that parent is the subsystem, not any specific controller. > > > > This series adds a set of experimental user-creatable objects: > > > > -object x-nvme-subsystem > > -object x-nvme-ns-nvm > > -object x-nvme-ns-zoned > > > > It also adds a new controller device (-device x-nvme-ctrl) that supports > > these new objects (and gets rid of a bunch of deprecated and confusing > > parameters). This new approach has a bunch of benefits (other than just > > fixing the hotplugging issues properly) - we also get support for some > > nice introspection through some new dynamic properties: > > > > (qemu) qom-get /machine/peripheral/nvme-ctrl-1 attached-namespaces > > [ > > "/objects/nvm-1", > > "/objects/zns-1" > > ] > > > > (qemu) qom-list /objects/zns-1 > > type (string) > > subsys (link<x-nvme-subsystem>) > > nsid (uint32) > > uuid (string) > > attached-ctrls (str) > > eui64 (string) > > blockdev (string) > > pi-first (bool) > > pi-type (NvmeProtInfoType) > > extended-lba (bool) > > metadata-size (uint16) > > lba-size (size) > > zone-descriptor-extension-size (size) > > zone-cross-read (bool) > > zone-max-open (uint32) > > zone-capacity (size) > > zone-size (size) > > zone-max-active (uint32) > > > > (qemu) qom-get /objects/zns-1 pi-type > > "none" > > > > (qemu) qom-get /objects/zns-1 eui64 > > "52:54:00:17:67:a0:40:15" > > > > (qemu) qom-get /objects/zns-1 zone-capacity > > 12582912 > > > > Currently, there are no shortcuts, so you have to define the full > > topology to get it up and running. Notice that the topology is explicit > > (the 'subsys' and 'attached-ctrls' links). There are no 'nvme-bus' > > anymore. > > > > -object x-nvme-subsystem,id=subsys0,subnqn=foo > > -device x-nvme-ctrl,id=nvme-ctrl-0,serial=foo,subsys=subsys0 > > -device x-nvme-ctrl,id=nvme-ctrl-1,serial=bar,subsys=subsys0 > > -drive id=nvm-1,file=nvm-1.img,format=raw,if=none,discard=unmap > > -object > > x-nvme-ns-nvm,id=nvm-1,blockdev=nvm-1,nsid=1,subsys=subsys0,attached-ctrls=nvme-ctrl-1 > > -drive id=nvm-2,file=nvm-2.img,format=raw,if=none,discard=unmap > > -object > > x-nvme-ns-nvm,id=nvm-2,blockdev=nvm-2,nsid=2,subsys=subsys0,attached-ctrls=nvme-ctrl-0 > > I may be wrong here, but my first gut feeling when seeing this was that > referencing the controller device in the namespace object feels > backwards. Usually, we have objects that are created independently and > then the devices reference them. > > Your need to use a machine_done notifier is probably related to that, > too, because it goes against the normal initialisation order, so you > have to wait. Error handling also isn't really possible in the notifier > any more, so this series seems to just print something to stderr, but > ignore the error otherwise. > > Did you consider passing a list of namespaces to the controller device > instead? > > I guess a problem that you have with both ways is that support for > list options isn't great in QemuOpts, which is still used both for > -object and -device in the system emulator... >
Heh. Exactly. The ability to better support lists with -object through QAPI is why I did it like this... Having the list of namespaces on the controller is preferable. I'll see what I can come up with. Thanks!
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