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Google Coral USB Edge TPU Accelerator on ESXi

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Several weeks back, I came across a really strange post on the VMTN communities asking how to change the Device ID (DID) and Vendor ID (VID) for a USB Device that has been passthrough to a VM from ESXi? The device in question is the Google Coral USB Edge TPU (Tensor Processing Unit) Accelerator, which is a relatively in-expensive device that can help accelerate machine learning (ML) inferencing. With all the buzz these days with Generative AI and ChatGPT, I can only imagine its popularity has grown even further but I did not realize how popular this device has been in the community, especially for those wanting to use it with ESXi.

The initial observation reported by this user and also by many others in the Coral community was that ESXi was showing the incorrect VID/DID for the Coral USB device and because of this, it was not working correctly when passthrough'ed to a VM and they were looking for a way to change the DID/VID value from 1a6e:089a (Global Unichip Corp.) to 18d1:9302 (Google Inc.).

Interestingly enough, a couple of weeks ago, my buddy Alan Renouf had also shared that he recently purchased the Coral USB device, so I figured I would check with him first to see if he was observing the same behavior that was being reported, which he was. I had been going through the Github reports to try better understand the issue and some of the previous workarounds that users had done including disabling the vmkusb module, which I definitely not recommended, especially for more recent releases of ESXi where that will simply disable all USB functionality to your ESXi host.

I still could not wrap my head around the issue as the reports did not make any sense in terms of the DID/VID not being claimed correctly or that it needed to change to properly function. This also did not make sense when speaking with our USB expert (Songtao who also developed our USB Network Native Driver for ESXi), so I decided to bite the bullet and purchase the Coral USB device, which apparently is difficult to obtain unless you overpay on Amazon, which I did.

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How to enable passthrough for USB Network Adapters claimed by ESXi CDCE Driver?

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As part of vSphere 7.0, ESXi now ships with a USB CDCE (Communication Device Class Ethernet) driver which can benefit customers with SB network adapters that support the CDCE specification as shared in this blog post HERE. This can especially be useful for those running a VMware Homelab where the onboard network adapter may not be supported and using a CDCE USB network adapter would allow you to install ESXi.

When a CDCE-supported USB network adapter is connected to an ESXi host, it will automatically be claimed by the CDCE driver as shown in the screenshot below.


If you are planning to use the USB network adapter for VMkernel traffic, then there is no workflow change like any other physical network adapter. However, if you intend to passthrough the USB network adapter to a VM, then you may find that it is not working as expected.


The reason for this is that ESXi has already claimed the USB device, assuming you wish to use it for VMkernel traffic. To change the behavior for a particular CDCE-supported USB network adapter, we just need to apply a USB Quirk which tells ESXi to ignore this adapter.

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Quick Tip - Enabling ESXi Coredumps to be stored on USB

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I was recently working with Engineering to reproduce an issue which causes an ESXi PSOD (Purple Screen of Death) and I wanted the generated ESXi coredump to simply write to the USB device, which I could easily grab.

As of ESXi 7.x, I know we had removed a few of the old ESXi kernel boot options for allowing ESXi to store coredumps on a USB device and the using the ESXi kernel boot option allowCoreDumpOnUsb=TRUE should now be used, however I was struggling to get it to work.

Since I was using a debug version of ESXi, I needed to install ESXi from scratch and I thought I could simpply add the required kernel option, as shown in the screenshot below, and I had assumed it would automatically configure the ESXi coredump file to be stored on the VMFS-L volume residing on the USB device.


After a couple of attempts, I finally realized that this particular ESXi kernel boot option, is literally that, a boot option that is only applicable after the initial ESXi installation. šŸ¤¦ Unlike other ESXi kernel boot options which can be used during the initial installation which would apply certain configuration changes, this setting applies after ESXi has been installed. Once I appended the setting, the ESXi coredump file was created in the VMFS-L volume and I was then able to reproduce the issue and generate vm-support bundle that included the coredump!