Re: [Qemu-discuss] virtio device instances identification by guest

[Michael S. Tsirkin]

On Thu, Nov 08, 2018 at 05:20:53PM +0600, Artem Pisarenko wrote:
> Ok, I found a way better, but it still not elegant, because depends on machine
> hardware configuration. One may use 'addr' property to assign address on PCI
> bus (and, if there are multiple PCI buses, identify bus somehow, but I didn't
> looked at).
> In my case on x86_64 target with default machine and given '-device
> virtio-net-pci,addr=<hex_8bit_id>.0,...' on command line guest application can
> get network interface name with:
> `ls /sys/devices/pci0000\:00/0000\:00\:<hex_8bit_id>.0/virtio*/net/`

I'm not sure I understand the requirements.
If you are after arbitrary strings, one way would be to add support
to vpd capability to devices... Want to try coding it up?

> 
> чт, 8 нояб. 2018 г. в 14:56, Artem Pisarenko <address@hidden>:
> 
>     Forgot to clarify that identification needs to be unique only to machine
>     scope. 'virtio-net-pci' has 'mac' property, but if user wants to
>     instantiate multiple such machines and connect them in one network, then
>     'mac' value also needs to be unique per this network. Thus, user have to
>     generate 'mac' from some <network host id> and <NIC id> parts and guest
>     should find network interface by mac address masked with <NIC id> part.

You need to create unique MACs anyway. If you don't it isn't guaranteed 
networking
will work.

>     Itsn't as elegant as in examples above. Although, it's better than
>     nothing...
> 
>     чт, 8 нояб. 2018 г. в 14:18, Artem Pisarenko <address@hidden>:
> 
>         Hi everyone,
> 
>         Is there are any way to make guest system able to identify specific
>         instances of virtio devices as specified by qemu user (on command line
>         or via qmp command)?
>         More specifically, I'm interested in virtio-net devices.
>         I know it's possible for some other devices:
>         - virtserialport/virtconsole have 'name=<name>' property and guest
>         application accesses serial device via "/dev/virtio-ports/<name>"
>         - virtio-9p-pci/virtfs have 'mount_tag=<mount_tag>' and guest
>         application mounts filesystem with "mount -t 9p -o trans=virtio
>         <mount_tag> ..."
>         But I cannot find any way to associate '-device virtio-net-pci'
>         instances with eth<X> network interfaces in guest.
> 
>         Thanks in advance,
>         Artem
> 
>