Re: [libvirt] [PATCH 0/3] add pci-bridge device and address type

在 2012-12-26三的 16:28 +0800，Osier Yang写道： > On 2012年12月26日 16:12, li guang wrote: >> 在 2012-12-26三的 15:38 +0800，Osier Yang写道： >>> On 2012年12月26日 09:00, liguang wrote: >>>> Now, it's unnecessary to arrange devices into multi-pci-bus, >>>> for example: >>>> <sound model='ac97'> >>>> <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/> >>>> </sound> >>>> <video> >>>> <model type='cirrus' vram='9216' heads='1'/> >>>> <address type='pci' domain='0x0000' bus='0x1' slot='0x02' function='0x0'/> >>>> </video> >>>> libvirt will complain about "bus != 0", >>>> fortunately, qemu supports pci-to-pci bridge, >>>> if we want to use multi-pci-bus, we can define >>>> 2 pci bridge devices then attach 1 to the other >>>> as a subordinate pci-bus, so, 2 pci-buses appear. >>>> for example: >>>> <pci-bridge type='root'/> >>>> <pci-bridge type='subordinate'> >>>> <address type='pci-bridge' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/> >>>> </pci-bridge> >>>> <sound model='ac97'> >>>> <address type='pci-bridge' domain='0x0000' bus='0x01' slot='0x02' function='0x0'/> >>>> </sound> >>>> <video> >>>> <model type='cirrus' vram='9216' heads='1'/> >>>> <address type='pci-bridge' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/> >>>> </video> >>> >>> I think this is rather not workable, E.g. how to known the video device >>> attached to which pci bridge if there are multiple pci bridges? >> >> please bear in mind bus 0 is root bridge, bus 1 is subordinate bridge, >> and so forth, which was implemented in my patch 2/3 > > That doesn't answer the question. video attached to root bridge(bus 0), slot 2 sound attached to bus 1 , slot 1 > >> >>> And the >>> new address type "pci-bridge" looks bogus, as the address properties of >>> a pci bridge are exactly same with a normal pci device. >>> >>> From the qemu patch: >>> >>> -device pci-bridge,id=bridge1 \ >>> -netdev user,id=u \ >>> -device ne2k_pci,id=net2,bus=bridge1,netdev=u >>> >>> I think what we only need is to describe the relapship between pci >>> bridge and pci bridge (if it's supported, the two types "root" and >>> "subordinate" are not enough to describe the relatioship), also pci >>> device and pci bridge. >> >> relationship between pci-bus and devices are embedded, just like >> pci.0, e.g. >> <address type='pci' domain='0x0000' bus='0x00' slot='0x04' >> function='0x0'/> >> means a device sitting on bus pci.0 slot 4 >> then after my changes >> <address type='pci-bridge' domain='0x0000' bus='0x00' slot='0x04' >> function='0x0'/> >> would have the same mean >> relationship between pci-bridges are primary and secondary, >> (as far as I know qemu doesn’t support multi-pci-bridges at present) >> so root and subordinate attribute may be enough, > > No, even it's not supported now, the proposed XML should be > designed compatible enough for future. Note that as long > as a new XML is added, it can't changed/removed for back-compact, > so when introducing new XMLs, you should consider the future. > > And on other hand, the introduced XML should be general > enough for all drivers, not only QEMU. > > Anyway, regardless of the current qemu implementation, I think > you should refer to the specification of PCI SGI, so that the > proposed XML could be compatible enough for the future. yes, I will, but any problem with the pci-bridge definition in XML? it's just a simple element. can you tell more details about problem of this new definition?

> >> every subordinate will attach to root bridge, and has its own slot. >> >>> >>> To describe the relationship between bridges, perhaps we will need >>> "parent" and "child" properties for<pcibridge> device. >>> >>> To describe the relatioship between a pci device and a pci bridge, >>> a property like "bridge" for general pci device should be enough. >>> In this case, another property for<pcibridge> is needed, to >>> indentify it, such as "id" or "name". >> >> only relationship is not enough, it's unsuitable for passing '-device >> pci-bridge' to qemu, so I define a new device and address type for >> pci-bridge in libvirt. >> >>> >>> Regards, >>> Osier >>> >>> >> >