On Wed, Jan 05, 2011 at 12:25:58PM -0700, Eric Blake wrote: > On 01/04/2011 02:17 AM, Alon Levy wrote: > > [focusing on the spicevmc chardev aspect] > > >> > >> <domain...> > >> <devices> > >> <smartcard mode='passthrough' name='xyz'> > >> <serial type='spicevmc'/> > >> </smartcard> > >> </devices> > >> </domain> > >> > >> maps to qemu -chardev spicevmc,id=smartcard,name=xyz -usb -device > >> usb-ccid -device ccid-card-passthru,chardev=xyz > >> > > > > ok, here you just mixed the id and name. I admit name is a bad, well, name, > > but it was already available as a parameter to chardev's (used as the filename > > for a file chardev). In the context of a spicevmc chardev the name is actually > > what I internally call a subtype. There are two subtypes/names that are valid > > currently: vdagent and smartcard. The id attribute is a global qemu tag that > > identifies a particular instance, so what needs to match is the chardev id > > and the chardev value given to the ccid-card-passthru device: > > > > >> And, given the goal that <smartcard mode='passthrough'> then has a child > >> element that describes the passthrough device, it also means that I > >> would be adding support for a top-level spicevmc chardev device, > >> unrelated to smartcards; would this need any additional XML parameters? > >> > > > > Right, again sorry for introducing it this way - exactly correct, the spicevmc > > is a separate entity. It is a new chardev, this is the chardev suggested last > > time I talked to libvirt when I tried to introduce a similarly named device > > called spicevmc. So instead of a superficial wrapper around virtio-serial I > > am introducing a chardev that can be used to connect to the spice server that > > is linked to the qemu process. The parameters for spicevmc are: > > id - this is the normal identifier that all chardev's must have. > > name - this distinguishes between the use of this chardev internal to spice, it > > can be of two values right now as I mentioned, 'vdagent' for use as the vdagent > > connection, and 'smartcard' for use by the smartcard channel. > > > >> <domain...> > >> <devices> > >> <serial type='spicevmc'> > >> <!-- anything else needed for a top-level spicevmc chardev? --> > >> </serial> > >> </devices> > >> </domain> > >> > > > > <serial type='spicevmc' id='xyz' name='vdagent'/> > > <serial type='spicevmc' id='xyz' name='smartcard'/> > > According to our existing XML: > http://libvirt.org/formatdomain.html#elementsConsole > > there are four categories of chardevs: <serial>, <parallel>, <console>, > and <channel>. Within each chardev, there are two optional > sub-elements: <source> describing the host's view of the chardev, and a > <target> describing the guest's view (the chardev type dictates whether > <source> must exist, and the chardev category dictates what <target> > must look like). > > It sounds to me like spicevmc is best described as a <channel>, since it > is exposing a spice channel for host communications rather than an > actual character device on the host. > > The chardev type of spicevmc (the type attribute under > <serial|parallel|console|channel>) does not fit in with any of the > existing channel types of 'stdio', 'file', 'vc', 'null', 'pty', 'dev', > 'pipe', 'tcp', 'udp', or 'unix', so it would be a new type 'spicevmc'. > It probably only makes sense to use type='spicevmc' with <channel>, so > the other three chardev types should probably reject it. > > When the chardev type is 'spicevmc', the <source> sub-element seems like > it is optional (since the spice connection has sane defaults), but if > provided, will provide the extra information that can also be provided > through the existing <graphics type='spice'> element, such as port='5903'. > > Meanwhile, since spicevmc is a <channel>, the <target> element must > specify a type (right now, the only types expected for <channel> are > 'guestfwd' and 'virtio'), so we're effectively adding two new types > ('vdagent' and 'smartcard'). > > So, I'm thinking that this XML representation matches the spicevmc chardev: > > <devices> > <channel type='spicevmc'/> > <source port='5903' tlsPort='5904' autoport='no' > listen='127.0.0.1'/> I got you until now - but what's with the port/tlsPort - all of that stuff belongs to the spice flag, and I'm pretty sure is already taken care of by some other tag (I guess <spice> probably?). This chardev is totally separate (sure, you need to be using spice for it to make sense, but there is not overlap in parameters, for instance you don't give a port nor a tlsPort to the spicevmc chardev). > <target type='smartcard'/> This looks right. > </channel> > </devices> > > In looking more at libvirt XML, I don't see any fields that match id > assignments; rather, libvirt auto-assigns unique ids in the form %s%d, > category, count, where category matches <channel> and count matches how > many <channel> devices are present. That is, the above xml would map to: > > qemu -chardev spicevmc,id=smartcard,name=channel1 > I hope you meant id=channel1,name=smartcard ? the id needs to be the same as the ccid-passthru uses. But I guess we determined that it's easiest to let the <smartcard mode="passthru"/> already add the spicevmc chardev itself? the usage of "-chardev spicevmc,id=xyz,type=smartcard" is only for a "-device ccid-card-passthru,chardev=xyz", so one won't appear without the other. The usage of "-chardev spicevmc,id=xyz,type=vdagent" is also just with the usage of spice, I'm guessing the existing <spice> tag (sorry, not familiar with it - I use qemu from shell scripts.. :/ ) should just always create this chardev, and libvirt will make sure it's id doesn't conflict with any other, i.e. for spice usage a spicevmc chardev used by a virtioserialport device: -chardev spicevmc,id=chardev1,name=vdagent -device virtserialport,chardev=chardev1,name=com.redhat.spice.0 This creates the virtioserialport device with the name the in-guest agent looks for, and ties it to the correct spice server interface via the spicevmc chardev. > > Hmm; getting spicevmc to work seems independent enough of getting > <smartcard> implemented by using existing <channel type='tcp'/>, so I'll > try to split my libvirt XML improvements into two batches. Should I > focus on <channel type='spicevmc'> or on <smartcard> first? I guess start with the smartcard first? Implement it without dealing with the spicevmc side - i.e. don't implement the passthru type first, or propose it but don't implement it. Then do the spicevmc part. I'm not particular on the order - both are required for RHEL 6.1 anyhow, and each is testable without the other (spicevmc with vdagent usage outlined above, and smartcard without spice by using it locally through libvirt). > > -- > Eric Blake eblake@xxxxxxxxxx +1-801-349-2682 > Libvirt virtualization library http://libvirt.org > -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list