Coral TPU PCI Passthrough
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I've read that those TPU are breaking the PCI specification, and therefore having issues when you do PCI passthrough with them. Maybe it was on the forum, last year or two
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@olivierlambert I saw that post in my initial search but it doesn't look like the OP replied with the PCI dump. Is there any hope for a workaround?
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You can continue here to provide details, maybe we'll see something obvious
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@olivierlambert Aside from the dump in my original post would you like me to run any additional commands to gather more data?
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@andSmv will take a look when he's around
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What's your exact model of Coral TPU by the way?
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@olivierlambert M.2 Accelerator B+M Key
https://coral.ai/products/m2-accelerator-bm#description -
So I've heard Qubes OS people did some patches to workaround the broken PCI spec for the device, I need to ask around more details about this.
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@andSmv I discussed with Marek from Qubes, he told me that might be relevant (or not): https://lore.kernel.org/xen-devel/20221114192100.1539267-2-marmarek@invisiblethingslab.com/
What do you think?
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Hello, sorry for late response (just discovered the topic)
With regards of Marek patches, I'm actually think it can worth a try (at least the patch seems to treat the problem where MSI-x PBA page is shared with other regs of the device), but there's some cons too:
- the patches are quite new (doesn't seems to be integrated yet).
- the patches can be applied to more recent Xen (not XCP-ng Xen), and even we could probably backport them, it potentially will require some significant work
- we are not 100% sure it's the issue (or the only issue)
So If this is a must have, we can go and do some digging to make it work (but still in the scope of "exeperimental" platform, not the production platform)
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We could probably try on a non-XCP-ng platform with a very recent "vanilla" Xen (+Marek patches) and see if it's fixed. If it is, then we could think about a potential backport when 8.3 will include a more recent Xen version
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@logical-systems I will check which Xen version the patches are easily applied and If you want I could give you a hand (if needed) to build and install your builded XEN, so you can test if this resolve your issue.
Unfortunatly we don't have the related HW (Coral TPU) to test it by ourselves.
UPDATE: the both patches apply to xen 4.17 (tag RELEASE-4.17.0)
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J jmccoy555 referenced this topic on
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Hi,
I'm researching XCP-NG as an alternative to my homelab VMware hypervisor.
A goal for me is to get proper USB passthrough of the Google Coral TPU.Did these patches make it work so passthrough to a VM is confirmed to be working?
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@andSmv said in Coral TPU PCI Passthrough:
@logical-systems I will check which Xen version the patches are easily applied and If you want I could give you a hand (if needed) to build and install your builded XEN, so you can test if this resolve your issue.
Unfortunatly we don't have the related HW (Coral TPU) to test it by ourselves.
UPDATE: the both patches apply to xen 4.17 (tag RELEASE-4.17.0)
So the above mentioned patches are included in the 4.17 that is currently available as a test version?
Or did you mean the patches worked on that version?
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Now we have Xen 4.17 in XCP-ng 8.3, that might work (ping @andSmv )
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@redakula Hello, unfortunately these patches are not in 4.17 Xen (and was never integrated in more recent Xen). So, to test it, you have to manually apply patches (normally should apply as is to 4.17) and rebuild your Xen.
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@andSmv
Damn - i was quick and have a coral m2 A+E coming in a few days
It's just for fun/learning so as long as it doesn't break my homelab too much i will be willing to test so we might get it included
Already using the 4.17 test version without a hitch since it came out. -
@andSmv
As expected the VM with the coral m2 crashes on boot.Where would i start with building a custom Xen? The Koji docs seem directed at authorized package maintainers so would i need to build the sources directly from Xen?
Feeling old admitting it was in the 2.6 days i last regularly built custom kernels
