[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: libxl / xen-pciback interaction [and 1 more messages]
On 17.03.2021 16:12, Ian Jackson wrote: > Jan Beulich writes ("libxl / xen-pciback interaction"): >> while trying to test a pciback fix for how SR-IOV VFs get placed in the >> guest PCI topology I noticed that my test VM would only ever see the 1st >> out of 3 VFs that I passed to it. As it turns out, the driver watches >> its own (backend) node, and upon first receiving notification it >> evaluates state found in xenstore to set up the backend device. >> Subsequently it switches the device to Initialised. After this switching, >> not further instances of the watch triggering would do anything. > > This makes it sound like this driver does not support hotplug. > >> While doing this it also occurred to me as odd how "num_devs" is >> actually used: It's not really a "number of devices" indicator, but >> instead a "next device has this number" one: libxl reads the present >> value and increments it by one for every new device. Destroying >> (hot-unplugging) of devices doesn't have any effect on the value. > > But this makes it sound like the driver *does* support hotplug. > > How does what libxl is doing differ from a setup, immediately followed > by a hot-add ? In the hot-add case libxl drives things through Reconfiguring state. I'm not sure this would be an appropriate (and backwards compatible) thing to do when initially populating xenstore. Jan
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