Hi all:
I have one question about PCI passthrough. I found that if I
created a VM with host pci device(cfg file as below), there were some xenstore
keys exsiting in /local/domain/0 and /local/domain/DomID/. Besides I found one
unknown device in device manager of Windows OS with Class ID FF80 from vendor
ID 5853. My questions are as below:
1. Why do we create frontend and backend key pairs in xenstore? I think
Passthrough is not PV, was it possible that we just used these keys to record
something?
2. After review the code, I think backend keys are used to record state
of hostdev, some codes will query something using these keys. But for frontend
keys, can we delete them?
3. if frontend keys exist in xenstore, then unknown device will appear in
device manager. Can we fix this? For an obsessive, he can't stand for this.
Cfg file as below:
builder = "hvm"
name = "win2008_server_r2_sp1_64"
viridian = 1
memory = 8192
maxmem = 8192
vcpus = 4
disk = [ '/mnt /win2008_server_ent_r2_sp1_64_gputhrough_vhd,vhd,xvda,rw' ]
vnc = 1
vnclisten = 'xxx.xxx.xxx.xxx'
vncdisplay = 0
usb = 1
usbdevice = ['tablet']
pci = ["0000:06:00.0"]
I use xen-4.8.0 version.
Xenstore keys
For domU
/local/domain/5/device/vkbd/0/backend = "/local/domain/0/backend/vkbd/5/0"
/local/domain/5/device/vkbd/0/backend-id = "0"
/local/domain/5/device/vkbd/0/state = "1"
/local/domain/5/device/pci = ""
/local/domain/5/device/pci/0 = ""
/local/domain/5/device/pci/0/backend = "/local/domain/0/backend/pci/5/0"
/local/domain/5/device/pci/0/backend-id = "0"
/local/domain/5/device/pci/0/state = "1"
/local/domain/5/control = ""
For dom0
/local/domain/0/backend/vkbd/5/0/feature-abs-pointer = "1"
/local/domain/0/backend/vkbd/5/0/hotplug-status = "connected"
/local/domain/0/backend/pci = ""
/local/domain/0/backend/pci/5 = ""
/local/domain/0/backend/pci/5/0 = ""
/local/domain/0/backend/pci/5/0/frontend = "/local/domain/5/device/pci/0"
/local/domain/0/backend/pci/5/0/frontend-id = "5"
/local/domain/0/backend/pci/5/0/online = "1"
/local/domain/0/backend/pci/5/0/state = "3"
/local/domain/0/backend/pci/5/0/domain = "win2008_server_r2_sp1_64"
/local/domain/0/backend/pci/5/0/key-0 = "0000:06:00.0"
/local/domain/0/backend/pci/5/0/dev-0 = "0000:06:00.0"
/local/domain/0/backend/pci/5/0/vdevfn-0 = "20"
/local/domain/0/backend/pci/5/0/opts-0 =
"msitranslate=0,power_mgmt=0,permissive=0"
/local/domain/0/backend/pci/5/0/state-0 = "3"
/local/domain/0/backend/pci/5/0/num_devs = "1"
/local/domain/0/backend/pci/5/0/vdev-0 = "0000:00:00.00"
/local/domain/0/backend/pci/5/0/root-0 = "0000:00"
/local/domain/0/backend/pci/5/0/root_num = "1"
/local/domain/5 = ""
/local/domain/5/vm = "/vm/81296e36-1576-4b58-bb6e-17dc2b4ea1f6"
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