ESXi not allowing 64bit guests, why?

[Forge64]

I've got a machine here that was happily running Linux + VMware Server, both 32 and 64bit guests. I previously had ESXi 3.5u4 on it, but the onboard NIC was trouble.

I installed ESXi 4.0 and the SATA required no hackery, and the NIC worked, and I was ecstatic.

Then I tried adding my VMs back to it via Converter. "Host doesn't support 64 bit guests".

I figured that had to be a goof, some problem with Converter.

Set up a new Vista64 guest from scratch, began install, crash "Your computer does not support 64 bit mode". WTF?

HP dc5800 with a Core 2 Quad Q6600. Has VT.

Why would it not be able to run 64bit guests under ESXi 4.0? It ran them under 3.5u4 and under Server 2.0 + Linux host.

[AndreTheGiant · Accepted solution]

Be sure that Virtualization (or VT) is enabled in BIOS.

Check also in HCL to see if your system is compliant:

http://WWW

Andre

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[admin]

See . This document is mainly aimed at hosted products, but you can use the ISO image to verify that VT-x is locked and enabled at boot. When you were using VMware Server, did you use the 'hv.enableIfUnlocked' setting to work around a BIOS bug? ESX does not recognize that configuration option.

[Forge64]

Now I feel dense. I forgot that I updated my system BIOS about a week or so ago. I'm guessing I hadn't run any 64bit VMs in the meantime, and the x64 autostarts were failing silently. Re-enabled VT-x in BIOS and it's working correctly now. Thanks.

[AndreTheGiant]

You're welcome.

Andre