[SOLVED] Problems with PCIe Passthrough (Timing?)

ProNatur

New Member
Feb 5, 2016
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Hello,

I use Proxmox 4.1 since the last month and it seems very good. Two Windows 2012R2 on a HP DL380 work correct and stable. I like it.

But there is one problem. I want to use a Gerdes PrimuX 2S0 E ISDN card (lspci result: 08:00.0 ISDN controller [0204]: Lattice Semiconductor Corporation Device [1204:e236]) on one of the VMs. I enabled passthrough in the config file of the VM (hostpci0: 08:00.0, pcie=1) and the card is recorgnized in the VM. Installing the drivers wasn't a problem and so I installed the fax software (Tobit David.fx 11).

When I try to send or receive a fax, the connection was established only sometimes. With this results, I talked to the Gerdes support and they told me to change the IRQ Latency from 2 ms to 16 ms because of the virtual environment. With this, I get always a stable connection to the other side. But the faxes aren't send correct. When the server trys to send the data, only the first block is sent correct. After 20 mm the content get corrupted. At the end, the software says, that fax is send correct.

With this in mind, I assume, that there is a problem with transfering the data to/from the card to the program because of the virtualisation. Perhaps a timing problem? Perhaps someone have seen such a behavior and could give me an tip, where to search to solve this problem.

Btw. a backup to a passthrough USB port with a harddisc works perfect.

Best regards,
Dirk
 
Couldn't something about with google... is it possible to change these settings directly in the Bios of the hostmachine?
 
Good idea, but what should I change?

I saw, that the card is using IRQ 16 and found some forum entries regarding this IRQ. Could this be the problem? Normally the answers suggest to disable all USB ports. This is in this case not possible.
 
Solved the problem by changing the used card: with a Dialogic Diva BRI-2 PCIe there are no problems anymore. Works perfect with Proxmox and Tobit David.fx in Windows 2012R2.
 

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