On Mon, Mar 15, 2021 at 02:00:58PM -0400, Igor Mammedov wrote: > In x86/ACPI world, linux distros are using predictable > network interface naming since systemd v197. Which on > QEMU based VMs results into path based naming scheme, > that names network interfaces based on PCI topology. > > With itm on has to plug NIC in exactly the same bus/slot, > which was used when disk image was first provisioned/configured > or one risks to loose network configuration due to NIC being > renamed to actually used topology. > That also restricts freedom to reshape PCI configuration of > VM without need to reconfigure used guest image. > > systemd also offers "onboard" naming scheme which is > preferred over PCI slot/topology one, provided that > firmware implements: > " > PCI Firmware Specification 3.1 > 4.6.7. DSM for Naming a PCI or PCI Express Device Under > Operating Systems > " > that allows to assign user defined index to PCI device, > which systemd will use to name NIC. For example, using > -device e1000,acpi-index=100 > guest will rename NIC to 'eno100', where 'eno' is default > prefix for "onboard" naming scheme. This doesn't require > any advance configuration on guest side to com in effect > at 'onboard' scheme takes priority over path based naming. > > Hope is that 'acpi-index' it will be easier to consume by > management layer, compared to forcing specific PCI topology > and/or having several disk image templates for different > topologies and will help to simplify process of spawning > VM from the same template without need to reconfigure > guest NIC. > > This patch adds, 'acpi-index'* property and wires up > a 32bit register on top of pci hotplug register block > to pass index value to AML code at runtime. > Following patch will add corresponding _DSM code and > wire it up to PCI devices described in ACPI.
You've illustrated usage & benefits with NICs, but IIUC, this feature is wired up for any PCI device. Are you aware of any usage of this feature for non-NIC devices ? Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
