On 06/24/19 12:18, Kevin Wolf wrote: > Am 24.06.2019 um 10:01 hat Klaus Birkelund geschrieben: >> On Thu, Jun 20, 2019 at 05:37:24PM +0200, Laszlo Ersek wrote: >>> On 06/17/19 10:12, Klaus Birkelund wrote: >>>> Hi all, >>>> >>>> I'm thinking about how to support multiple namespaces in the NVMe >>>> device. My first idea was to add a "namespaces" property array to the >>>> device that references blockdevs, but as Laszlo writes below, this might >>>> not be the best idea. It also makes it troublesome to add per-namespace >>>> parameters (which is something I will be required to do for other >>>> reasons). Some of you might remember my first attempt at this that >>>> included adding a new block driver (derived from raw) that could be >>>> given certain parameters that would then be stored in the image. But I >>>> understand that this is a no-go, and I can see why. >>>> >>>> I guess the optimal way would be such that the parameters was something >>>> like: >>>> >>>> -blockdev >>>> raw,node-name=blk_ns1,file.driver=file,file.filename=blk_ns1.img >>>> -blockdev >>>> raw,node-name=blk_ns2,file.driver=file,file.filename=blk_ns2.img >>>> -device nvme-ns,drive=blk_ns1,ns-specific-options (nsfeat,mc,dlfeat)... >>>> -device nvme-ns,drive=blk_ns2,... >>>> -device nvme,... >>>> >>>> My question is how to state the parent/child relationship between the >>>> nvme and nvme-ns devices. I've been looking at how ide and virtio does >>>> this, and maybe a "bus" is the right way to go? >>> >>> I've added Markus to the address list, because of this question. No >>> other (new) comments from me on the thread starter at this time, just >>> keeping the full context. >>> >> >> Hi all, >> >> I've succesfully implemented this by introducing a new 'nvme-ns' device >> model. The nvme device creates a bus named from the device id ('id' >> parameter) and the nvme-ns devices are then registered on this. >> >> This results in an nvme device being creates like this (two namespaces >> example): >> >> -drive file=nvme0n1.img,if=none,id=disk1 >> -drive file=nvme0n2.img,if=none,id=disk2 >> -device nvme,serial=deadbeef,id=nvme0 >> -device nvme-ns,drive=disk1,bus=nvme0,nsid=1 >> -device nvme-ns,drive=disk2,bus=nvme0,nsid=2 >> >> How does that look as a way forward? > > This looks very similar to what other devices do (one bus controller > that has multiple devices on its but), so I like it.
+1 Also, I believe it's more modern nowadays to express the same example with "blockdev" syntax, rather than "drive". (Not that I could suggest the exact spelling for that :)) I don't expect the modern syntax to behave differently, I just guess it's better to stick with the new in examples / commit messages etc. > The thing that is special here is that -device nvme is already a block > device by itself that can take a drive property. So how does this play > together? Can I choose to either specify a drive directly for the nvme > device or nvme-ns devices, but when I do both, I will get an error? What > happens if I don't specify a drive for nvme, but also don't add nvme-ns > devices? Great questions! Thanks! Laszlo