On 25.09.19 11:12, Gerd Hoffmann wrote: > Hi, > >> If you want to add hotplug to microvm, you can reuse the existing code >> for CPU and memory hotplug controllers, and write drivers for them in >> Linux's drivers/platform. The drivers would basically do what the ACPI >> AML tells the interpreter to do. > > How would the linux kernel detect those devices? > > I guess that wouldn't be ACPI, seems everyone wants avoid it[1]. > > So device tree on x86? Something else? > > cheers, > Gerd > > [1] Not clear to me why, some minimal ACPI tables listing our > devices (isa-serial, fw_cfg, ...) doesn't look unreasonable > to me. We could also make virtio-mmio discoverable that way. > Also we could do acpi cpu hotplug without having to write those > linux platform drivers. We would need a sysbus-acpi device though, > but given that most acpi code is already separated out so piix and > q35 can share it it should not be that hard to wire up. > Just to make one thing clear, the same could be used for DIMM based memory hotplug, too. virtio-mem is not simply exposing DIMMs to a guest using virtio. It's even designed to co-exist with DIMM based memory hotplug. -- Thanks, David / dhildenb
