ASM1166 - No passthrough with rombar=1 possible - PVE9 bug?

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brightrgb

Active Member
Dec 26, 2021
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Hello,

I want to passthrough an ASM1166 M.2.PCIe card to an VM.
It only works, if I set rombar=0.
Also it seems in PVE9 you don't have to blacklist the driver of the ASM1166, because PVE did this alone.

Is it new, that blacklisting the driver is no longer needed?
And is it a problem, if I set rombar=0. Can I get errors or stability problems?

In another thread I found, that it could also work to set:
libata.force=nolpm
What does this do and is this the better option than set rombar=0?
 
why? please use virtualisation on all parts of the Proxmox VE Concept!
Don't use Hardware any more direct, so you get stream line functionality.
If you want a NAS then buy one or build one independent on its own Hardwarebasis.
 
brightrgb said:
I want to passthrough an ASM1166 M.2.PCIe card to an VM.
It only works, if I set rombar=0.
Click to expand...
Congratulations, your hardware works with PCI(e) passthrough which is unfortunately not that common.
brightrgb said:
And is it a problem, if I set rombar=0. Can I get errors or stability problems?
Click to expand...
Probably not. This is a common option to try enabled and/or disabled when doing PCI(e) passthrough.
brightrgb said:
In another thread I found, that it could also work to set:
libata.force=nolpm
What does this do and is this the better option than set rombar=0?
Click to expand...
Search for libata.force and then lookup nolpm in the documentation: https://www.kernel.org/doc/html/v6.17/admin-guide/kernel-parameters.html
 
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brightrgb said:
Could it be possible, that in earlier proxmox kernels the default value was libata.force=nolpm?
Click to expand...
No, as it would not make sense to disable power management for all SATA controllers. But drivers do get fixes, improvements and occasional new bugs on every new kernel version.

Please note that none of this is Proxmox specific as the PCI(e) passthrough (with ROMBar enabled/disabled) is standard KVM Linux technology and libata is a standard Linux drivers.
 
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leesteken said:
Please note that none of this is Proxmox specific as the PCI(e) passthrough (with ROMBar enabled/disabled) is standard KVM Linux technology and libata is a standard Linux drivers.
Click to expand...
Thank you.
Than I will stay with rombar=0 and try rombar=1 after the next big PVE update.
Maybe it will work than. Otherwise I hope I never get an problem with rombar=0.

And thanks again for your help with the other issue (other thread).
I think it's great that I can passthrough two PCIe devices to different VMs using the M.2 PCIe passthrough trick without the AES patch.
I would never have thought that the M2 slot could be well used for passthrough!
Even though the B550 boards have such poor IOMMU groups. Thanks again!
 
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