[Qemu-devel] Advice on some configuration parameters

[Fabio Fantoni]

I'm making patches to enable some qemu upstream features in xen that are 
missing in libxl.
I'm trying to do it just by giving arguments to qemu, and I want them to 
be dynamic (e.g. without physical addresses if possible) and concise.

I'm confused about usb configuration.

Looking at what virt-manager does, it seems that you set the 
usbredirection in channels like this:
-chardev spicevmc,id=charredir0,name=usbredir -device 
usb-redir,chardev=charredir0,id=redir0

At the moment I'm defining the physical usb devices like this:
-readconfig /etc/qemu/ich9-ehci-uhci.cfg

If I try to set up virt-manager so that it doesn't point to a file, it 
uses this configuration:

-device ich9-usb-ehci1,id=usb,bus=pci.0,addr=0x5.0x7
-device 
ich9-usb-uhci1,masterbus=usb.0,firstport=0,bus=pci.0,multifunction=on,addr=0x5
-device ich9-usb-uhci2,masterbus=usb.0,firstport=2,bus=pci.0,addr=0x5.0x1
-device ich9-usb-uhci3,masterbus=usb.0,firstport=4,bus=pci.0,addr=0x5.0x2

This seems to differ from the configuration file, e.g. you have 
multifunzion=on only on the first uhci, besides I can't understand how 
many physical ports are defined. I tried setting 9 usbredirection 
channels in virt-manager but that configuration doesn't change and no 
errors are reported, but I doubt that physical ports are being define 
dynamically.

Can you omit physical addresses?
I searched the web but I can't find detailed informations about it. Can 
someone explain in detail how you are supposed to configure usb physical 
ports? I want to enable both usb redirection and usb passthrough in a 
dynamic and concise manner.

About spice vdagent at the moment I'm using this configuration that 
seems to work:
-device virtio-serial -chardev spicevmc,id=vdagent,name=vdagent -device 
virtserialport,chardev=vdagent,name=com.redhat.spice.0

But I noticed that virt-manager use this slightly different one:
-chardev pty,id=charserial0 -device 
isa-serial,chardev=charserial0,id=serial0 -chardev 
spicevmc,id=charchannel0,name=vdagent -device 
virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,name=com.redhat.spice.0

Are there any problem with the more concise one I'm using?

Thanks for any reply.

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