Update to VMWare ESXi 8.0 with Unsupported CPUs

Obligatory: DON’T DO THIS IN A PRODUCTION ENVIRONMENT, YOU SHOULDN’T REALLY DO THIS AT ALL

I use two Atom C2550 servers in my homelab so I can have a little redundancy and can offload some low priority, low CPU intensive servers off my main server, but the new ESXi 8.0 doesn’t support them any longer. Here are the steps I used to rectify the situation. It works with both VCenter Images and command line updates.

Step 1: Edit /bootbank/boot.cfg & /altbootbank/boot.cfg and and add “allowLegacyCPU=true” (no quotes, a space between options) on the “kernelopt” line, then reboot. Example:

Step 2: (Skip below for command line) You can now use the Image Update built into VSphere to update the unsupported CPU.

Alternative Step 2: I use this website to get the command line to update to a specific version: esxi-patches.v-front.de add “–no-hardware-warning” (no quotes) to the update command. Run the command (it took a few minutes of not doing anything) then reboot.
My example command:

esxcli network firewall ruleset set -e true -r httpClient
esxcli software profile update  -p ESXi-8.0a-20842819-standard -d https://hostupdate.vmware.com/software/VUM/PRODUCTION/main/vmw-depot-index.xml  --no-hardware-warning
esxcli network firewall ruleset set -e false -r httpClient

Result:

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About the Author: JoeKewle

I have been working in the IT industry for about 20 years. I have a BS in Computer Science, and a MS in IT Management. I currently work mostly with Windows Server, VMWare, and other Microsoft technologies. I also have a pretty overkill homelab that I tinker with. I put up this site to hopefully document stupid stuff I find, or stuff I spent way too long figuring out so maybe I can help someone.

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