On 7/20/21 9:10 PM, Thanos Makatos wrote: >> On Mon, Jul 12, 2021 at 01:24:07PM +0000, Thanos Makatos wrote: >>> We're working on implementing a virtual NVMe controller based on SPDK >> and a multiprocess-qemu branch that uses the vfio-user. We're facing a >> problem where the existing API doesn't allow us to tell QEMU from which >> NVMe namespace we'd like SeaBIOS to boot from. >>> >>> How can we solve this problem? Can we add a parameter to the '-boot' >> option, e.g. '-boot path=/devices/pciblah/...@namespace0'? AFAIK VFIO >> should have the same problem. >>> >>> The corresponding SeaBIOS patch can be found in >> https://mail.coreboot.org/hyperkitty/list/seab...@seabios.org/thread/2Q7 >> NPH7TJNHK6JGPHQL7755HILO23ISN/ >> >> Hi, >> I have CCed Gerd Hoffmann on a hunch that he may have ideas. >> >> Yes, I think the path needs to include the Namespace ID similar to how >> SCSI boot paths include the target/channel/LUN. > > Just to make sure I've explained the problem correctly, what we need to fix > is not specific to NVMe: we want to be able to boot from any PCI device, so > we'd need something like '-boot /devices/pciblah'. Specifically, for NVMe we > might want to specify the namespace (as we can't necessarily assume that the > first one must be used), therefore we'd have to add the '/namespace0' bit. > For other kinds of PCI devices, we'd have to append something different. > > Would such a change be acceptable?
FWIW -boot path= sounds a good way to solve this problem, as long as you succeed at not breaking the legacy bootdevice.c :) > >> >> When the SeaBIOS NVMe driver probes the controller is should discover >> the available Namespaces and set up individual drives for each >> Namespace. That would be analogous to virtio_scsi_add_lun(). > > Setting up an individual drive can easily exhaust SeaBIOS's limited memory, > so it's better to either probe the specified namespace or probe the first > active one. I've sent a patch here: > https://mail.coreboot.org/hyperkitty/list/seab...@seabios.org/message/TKKUCH5PYZPXZG3NA2F5SALUFUVUYDZG/ > >
