Re:Re: how hotplug devices onto pcie-to-pci-bridge
Hi, Laine Stump and Oleg Vasilev:
1. Laine, what is 'conventional PCI device'? in my case they are all virtio
device.
2. Followed your guide,succeed in hotplug. but there are lots of problems after hotplug.
I think problems are more related to qemu.
2.1) disk devices(qcow2,virio) hotpluged onto pci-bridge can not alloc bar resource.
2.2) disk devices(qcow2,virio) are staticly pluged to pci-bridge can not be found by
guest os.
those devices are on pci bus, but can not be recognized by guest os, no block
device are probed.
qemu qemu-6.2.0
-----hotplug error message--------
[ 1067.577384] pci 0000:06:02.0: [1af4:1001] type 00 class 0x010000
[ 1067.578312] pci 0000:06:02.0: reg 0x10: [io 0x0000-0x007f]
[ 1067.578794] pci 0000:06:02.0: reg 0x14: [mem 0x00000000-0x00000fff]
[ 1067.579419] pci 0000:06:02.0: reg 0x20: [mem 0x00000000-0x00003fff 64bit pref]
[ 1067.581592] pci 0000:06:02.0: BAR 4: no space for [mem size 0x00004000 64bit pref]
[ 1067.581942] pci 0000:06:02.0: BAR 4: failed to assign [mem size 0x00004000 64bit pref]
[ 1067.582264] pci 0000:06:02.0: BAR 1: no space for [mem size 0x00001000]
[ 1067.582625] pci 0000:06:02.0: BAR 1: failed to assign [mem size 0x00001000]
[ 1067.582942] pci 0000:06:02.0: BAR 0: no space for [io size 0x0080]
[ 1067.583253] pci 0000:06:02.0: BAR 0: failed to assign [io size 0x0080]
[ 1067.584019] PCI Interrupt Link [GSIE] enabled at IRQ 20
[ 1067.584749] virtio-pci 0000:06:02.0: virtio_pci: leaving for legacy driver
[ 1067.585296] virtio-pci: probe of 0000:06:02.0 failed with error -12
-------staticly plug------------
[ 0.680299] pci 0000:06:02.0: [1af4:1001] type 00 class 0x010000
[ 0.683035] pci 0000:06:02.0: reg 0x10: [io 0xc080-0xc0ff]
[ 0.688036] pci 0000:06:02.0: reg 0x14: [mem 0xfca01000-0xfca01fff]
[ 0.700040] pci 0000:06:02.0: reg 0x20: [mem 0xfb404000-0xfb407fff 64bit pref]
--------------------------------------
At 2022-11-04 05:28:47, "Laine Stump" <laine(a)laine.org> wrote:
On 11/3/22 6:35 AM, longguang.yue wrote:
> Hi, all
> I have add two pcie-to-pci-bridge controllers, how hotplug devices
> onto this two controllers? and libvirt knows to plug onto pci-bridge
> when there are no pcie-ports.
> defaultly libvirt plugs devices onto pcie-port.
Do you mean you want hotplugged devices to be placed on the
pcie-to-pci-bridge even though there are unused pci-root-ports?
You can force a new device to be hotplugged to a particular slot of a
particular controller by including the <address> element in the XML of
the device you attach - whatever controller/slot/function you specify
there is what libvirt will use (practically speaking the function must
be 0).
My recollection is that, *if the device is a conventional PCI device
(and not a PCIe device) then libvirt will anyway attempt to find a an
open conventional PCI slot, which would be found only on the
pcie-to-pci-bridge. However, very few devices are actually conventional
PCI, so this will very rarely happen automatically (I haven't looked at
that code in a long time, and retain no specific memory, but I think the
only emulated device that is conventional PCI is a watchdog device or
something)
So, if libvirt is selecting a pcie-root-port to plug in a device, that's
because the device is a PCIe device. If you want to force it to do
otherwise, you'll need to manually specify the address (just set "bus"
of the address to the "index" of the controller, set "slot" to an
unoccupied slot (1-31), and set domain and function to 0).
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