[SOLVED] PCIE passthrough - how?

oldfart

Well-Known Member
May 14, 2019
40
2
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Proxmox 8.0.3
Trying to passthrough a PCIE TV decoder
done all the modules stuff

Code:
lspci -nnk
01:00.0 Multimedia video controller [0400]: Conexant Systems, Inc. CX23887/8 PCIe Broadcast Audio and Video Decoder with 3D Comb [14f1:8880] (rev 04)

lspci -n -s 01:00.0
01:00.0 0400: 14f1:8880 (rev 04)

Code:
find /sys/kernel/iommu_groups/ -type l |sort
/sys/kernel/iommu_groups/23/devices/0000:01:00.0

using GUI
VM | hardware | add | pci device
Mapped device is empty (as expected)

If I add Raw device 0000:01:00.0 Conexant Systems IOMMU 23
the VM will not start with error 'Unable to read tail (got 0 bytes)'

qm set VMID -hostpci0 01:00.0
PCIE device is NOT passed through

So how do I get this card to my VM?
 
Maybe I can help here,

First google for "proxmox iommu cmdline"

Than, add the device in mappings (in your Datacenter(top of proxmox)

Than you can add the card via mapping. If not working, I will look again, but now I have to go to bed now.

I have successfully passthrough my PCie nic card. With this way.
 
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Thanks for the reply
The mapping works
I still get an error when starting the VM
'Unable to read tail (got 0 bytes)''
 
Solved
lspci -nnk
01:00.0 Multimedia video controller [0400]: Conexant Systems, Inc. CX23887/8

however
lsmod | grep cx
does not report cx23887 drivers, but does report cx23885
so, add the following to proxmox /etc/modprobe.d/blacklist.conf:

blacklist cx23885

and I can now passthrough the pcie card
 
Last edited:
Mapped device is empty (as expected)

What do people mean when they say this? Why is it expected for the mapped device to be empty?
And what's the difference between Mapped Device and Raw Device

I scourged the internet and could not find an answer

1710453484896.png
1710453500682.png
 
What do people mean when they say this? Why is it expected for the mapped device to be empty?
And what's the difference between Mapped Device and Raw Device

I scourged the internet and could not find an answer
I am also looking for more information on the differences between Mapped Device and Raw Device. Did you find any documentation since posting?
 

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