How to install ESXi 8 on an Unsupported Processor

Installing ESXi 8 with an unsupported CPU

VMware ESXi 8 has discontinued support for many older CPU models, as described in Broadcom’s 318697 article (Discontinuation and Removal of CPU Support in vSphere Versions). The result is the following error message if you try to install ESXi 8 on a server with an unsupported CPU:

Note that VMware KB 82794 is the same as the Broadcom article mentioned earlier. The list of unsupported CPUs in VMware vSphere 8 is very extensive and includes Intel and AMD models.

VMware vSphere 8.0x Intel CPU Support Discontinued List:

VMware vSphere 8.0x AMD CPU Support Discontinued List:

This list does not include all desktop/laptop CPU models. If your goal is to install ESXi 8 in a lab environment, how can you skip the CPU check step?

Keep in mind that installing ESXI 8 on an unsupported processor is not recommended in any operating environment.

To get past this error at boot, follow these steps:

1. Reboot the system from the boot media.
2. After displaying the ESXi boot menu, when the phrase “Loading ESXi Installer” starts displaying, press SHIFT+O within 5 seconds to add boot options.
3. Enter the phrase “allowLegacyCPU=true” at the end of the line. Here’s how:

<ENTER: Apply options and boot>
> runweasel cdromBoot allowLegacyCPU=true

Press Enter and continue the installation normally. Note that you may still encounter issues.

ESXi 8.0 Update 2 requires processors that support the XSAVE command, otherwise you won’t be able to upgrade, and it means you’ll need to have at least one Intel Sandy Bridge or AMD Bulldozer processor or newer models. For an interactive installation of ESXi, it won’t be a problem, but for an automatic installation of ESXi using Kickstart, this can be problematic because you will still need to manually press Enter to begin the installation.

There is a solution to this issue, which is explained in this article:

Yes, and there are actually several options that can be sent to the ESXi Kickstart script depending on which pre-check messages you want to ignore for automatic installation.

• –ignoreprereqwarnings – ignores warning messages.
• –ignoreprereqerrors – ignores error messages.
• –forceunsupportedinstall – ignores error/warning messages for outdated processors.

Also remember that the next version of vSphere (9.0) will not support other processor families:

Intel Skylake processors: Intel has moved the generation of Skylake processors to the ESU (End of Servicing Update) / EOSL (End of Servicing Lifetime) phase. This includes the Xeon-Scalable Processors (SP) series, which will be supported until December 31, 2023. For this reason, VMware has planned to discontinue support for Intel Skylake family processors in future major versions of vSphere after version 8.0.x.