Strange VT issue

Hi All,

I don't know if anyone has experienced this type of issue before but I decided to put 2008 r2 on to my lab setup on vmware workstation to do some testing, but initially the vm guest kept producing errors saying that I could not run a 64bit guest. I checked the BIOS and VT was definitely enabled and I have a VT capable CPU. I went back in to vmware and I got the same errors. I went back into the BIOS and disabled the VT and then re-enabled it. This time I went back into vmware and it was working.

Anyone had that before?

Cheers,

Pash

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JDMurray

Disable VT->reboot->Enable VT->reboot fixed it? Is there an update for your BIOS that fixes any VT-related problems?

MentholMoose

Pash wrote: »

Hi All,

I don't know if anyone has experienced this type of issue before but I decided to put 2008 r2 on to my lab setup on vmware workstation to do some testing, but initially the vm guest kept producing errors saying that I could not run a 64bit guest. I checked the BIOS and VT was definitely enabled and I have a VT capable CPU. I went back in to vmware and I got the same errors. I went back into the BIOS and disabled the VT and then re-enabled it. This time I went back into vmware and it was working.

Anyone had that before?

Cheers,

Pash

What is the host OS?

ajs1976

Just had a similiar issue with 64-bit 2008 R2 guest on ESXi. VT was disabled at first, but still had the error after enabling it and even rebooting. Had to shut the server down, then power back on to get the change to apply.

tiersten

ajs1976 wrote: »

Just had a similiar issue with 64-bit 2008 R2 guest on ESXi. VT was disabled at first, but still had the error after enabling it and even rebooting. Had to shut the server down, then power back on to get the change to apply.

Thats normal. You need to do a hard reset or powercycle the CPU if you're altering the Intel VT MSR bit.

tiersten

Pash wrote: »

I don't know if anyone has experienced this type of issue before but I decided to put 2008 r2 on to my lab setup on vmware workstation to do some testing, but initially the vm guest kept producing errors saying that I could not run a 64bit guest. I checked the BIOS and VT was definitely enabled and I have a VT capable CPU. I went back in to vmware and I got the same errors. I went back into the BIOS and disabled the VT and then re-enabled it. This time I went back into vmware and it was working.

Buggy BIOS, BIOS that doesn't do a automatic reset or you've not reset properly after altering the VT setting.

Hyper-Me

tiersten wrote: »

Thats normal. You need to do a hard reset or powercycle the CPU if you're altering the Intel VT MSR bit.

Bingo.

When enabling HAV you always need to do a hard reset on the system, a soft reset usually wont cut it.

JDMurray

Hyper-Me wrote: »

Bingo.

When enabling HAV you always need to do a hard reset on the system, a soft reset usually wont cut it.

That's good to know. But in Pash's case, it sounds like VT had already been set on that server through many power cycles. I'm thinking there's a bug in the BIOS too.

Hyper-Me

JDMurray wrote: »

That's good to know. But in Pash's case, it sounds like VT had already been set on that server through many power cycles. I'm thinking there's a bug in the BIOS too.

Its certainly possible there is a bug, and an upgrade flash may be in order.

Though he didnt specifically say he hard cycled after it was turned on (just that it was on when he checked, but that could still mean the machine hadnt been hard reset since it was enabled)

Pash

Sorry I should of mentioned, this was on my desktop. VT was enabled before hand, had to switch it on and off again exactly like JD said.

The BIOS version is fairly up to date, but looking at the release notes, no VT issues addressed in any newer releases anyway.

I was just curious if anyone had that issue before, its the Phoenix Award BIOS on a abit IP35 mboard.

tiersten

Pash wrote: »

Sorry I should of mentioned, this was on my desktop. VT was enabled before hand, had to switch it on and off again exactly like JD said.

The BIOS version is fairly up to date, but looking at the release notes, no VT issues addressed in any newer releases anyway.

I was just curious if anyone had that issue before, its the Phoenix Award BIOS on a abit IP35 mboard.

It doesn't really make much sense though as to why you had to toggle it to make it work though. The way that preferences are set for Phoenix BIOSes is that there are a bunch of single byte variables in NVRAM which are read to show the current state in setup and are also tested against to enable/disable whatever feature it controls. The BIOS code that does the MSR bits for VT is fairly straightforward if it is anything like the versions I've looked at. There isn't much that could go wrong in that portion of the code.

The best guess for why you had to do it is what JD said and its just a buggy BIOS.

If you know the location of the NVRAM variable for VT you can toggle it directly. I did this for my VAIO laptop because Sony don't support VT on that model and they've actually hidden the menu option in the BIOS setup. The backend code is still there that enables/disables VT based on this NVRAM variable. Modifying the BIOS code itself to reenable the menu option is risky so the alternative was to alter the NVRAM variable. The worst case scenario would be that I have to dismantle the laptop enough to reach the coin Lithium cell inside.

JDMurray

I just discovered Dell PowerEdge 1950 servers also need a cold boot to set their VT bit despite the "Virtualization Technology" setting in the BIOS displaying "Enabled" after a warm boot. I'll check if the R610 replacements for the 1950 need the same. Probably do as well.

Hyper-Me

JDMurray wrote: »

I just discovered Dell PowerEdge 1950 servers also need a cold boot to set their VT bit despite the "Virtualization Technology" setting in the BIOS displaying "Enabled" after a warm boot. I'll check if the R610 replacements for the 1950 need the same. Probably do as well.

Ive seen some R700s and some 2950 series III's do this as well, but not all of them. All at the same BIOS revision as well.