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12 Replies Last post: Jul 20, 2009 8:55 AM by jhp7395
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Help with cpu id mask

Jun 10, 2009 12:43 PM

Click to view jhp7395's profile Novice jhp7395 13 posts since
Jun 8, 2006

Hello, I have looked at a number of articles on how to calculate the cpuid mask for vmotion, but I don't quite get it. Could someone help me with this? I ran the CPU Idenfication Utility on both machines (PE6850, and Precision 690 - I know this is not a supported box). Here are the results:

1D1ECX was the only register with differences. The 6850 has 0x000065bd, and the 690 has 0x0004e3bd.

1D1EDX were both the same with 0xbfebfbff

1D81EXC were the same with 0x00000001

1D81EDX were the same with 0x20100000

So I don't know how to mask out the 3rd, 4th, and 5th byte for the 1D1ECX register. Any help would be appreciated.

Reply Re: Help with cpu id mask Jun 11, 2009 9:59 PM
Click to view AndreTheGiant's profile Guru AndreTheGiant 5,643 posts since
Aug 28, 2008
There is also an official Dell document:
http://www.dell.com/downloads/global/solutions/vmotion_compatiblity_matix.pdf

But why you do not use EVC? Is much simpler.

Andre
**if you found this or any other answer useful please consider allocating points for helpful or correct answers
Reply Re: Help with cpu id mask Jun 12, 2009 6:26 AM
in response to: AndreTheGiant
Click to view jhp7395's profile Novice jhp7395 13 posts since
Jun 8, 2006

The 690's support EVC, but the 6850, to my disappointment, does not. In the meantime, I was trying different combinations with the level 1 eax, ecx, and edx masks, and got one to work, BUT only for Windows XP/2003 guests. My 2008 servers take 10x longer to boot, and then there are problems with system devices not having resources. So I am still stuck there.

When you vmotion a vm, the message will tell you what the required mask should be, but when I try that, it doesn't work. Does anyone know if you should be able to determine the mask by the vmotion error dialogue?

BTW, the link you posted is broken, but I have seen that document before.

Attached is a screenshot of the masks that allow XP/2003 guest to vmotion.

Attachments:
Reply Re: Help with cpu id mask Jun 12, 2009 7:44 AM
in response to: jhp7395
Click to view AndreTheGiant's profile Guru AndreTheGiant 5,643 posts since
Aug 28, 2008
As I rember there is also a problem with the NX bit (the BIOS default change in BIOS 2.x).
Have you tried to disable it?

Andre
**if you found this or any other answer useful please consider allocating points for helpful or correct answers
Reply Re: Help with cpu id mask Jul 16, 2009 9:00 AM
in response to: AndreTheGiant
Click to view jhp7395's profile Novice jhp7395 13 posts since
Jun 8, 2006
Andre, I'm just getting back to this now. Your suggestion for disabling the nx bit worked for my 2008 64bit guests, but it is still a problem for the 32bit 2008 guests. Do you have any other suggestions?
Reply Re: Help with cpu id mask Jul 16, 2009 9:08 AM
in response to: jhp7395
Click to view AndreTheGiant's profile Guru AndreTheGiant 5,643 posts since
Aug 28, 2008
No more idea, sorry.
You have probably also to play with CPUID masking.

Andre
Reply Re: Help with cpu id mask Jul 16, 2009 9:09 AM
in response to: AndreTheGiant
Click to view jhp7395's profile Novice jhp7395 13 posts since
Jun 8, 2006
Okay, thanks very much for your help. I will see if any more tinkering with cpuid masks help, and will post the results here.
Reply Re: Help with cpu id mask Jul 16, 2009 9:16 AM
in response to: jhp7395
Click to view AndreTheGiant's profile Guru AndreTheGiant 5,643 posts since
Aug 28, 2008
It's a lot of time that I do not use CPUID Mask (thanks to EVC).
But in the past I've always used the CPUID ISO from VMware too check CPU feature:
http://download3.vmware.com/software/vi/VMware-CPU-Compatibility-e.x.p-160658.zip

See also:
http://www.vmware.com/files/pdf/vmotion_info_guide.pdf

Andre
Reply Re: Help with cpu id mask Jul 16, 2009 9:36 AM
in response to: AndreTheGiant
Click to view jhp7395's profile Novice jhp7395 13 posts since
Jun 8, 2006

I actually used the CPUID ISO, and derived the mask as shown in my initial post. It looks like the link you posted has an updated version from the one I used. Maybe I'll try that and see if there are any differences. Maybe I should also ask if you know of a way to enable EVC on the Dell 6850? It isn't that old of a server, so it should seem it would support this.

thanks, Jack

Reply Re: Help with cpu id mask Jul 16, 2009 9:43 AM
in response to: jhp7395
Click to view AndreTheGiant's profile Guru AndreTheGiant 5,643 posts since
Aug 28, 2008
also ask if you know of a way to enable EVC on the Dell 6850?

You need Intel VT enabled to use EVC.
Probably Dell 6850 CPU doesn't have it (I do not remember).

But you are able to run the x64 VMs also on Dell 6850 (as I see in the previous post)?

Andre
Reply Re: Help with cpu id mask Jul 16, 2009 9:52 AM
in response to: AndreTheGiant
Click to view jhp7395's profile Novice jhp7395 13 posts since
Jun 8, 2006
Yes, the 6850 has Intel VT, it runs both 32 and 64 bit guests fine, and remember checking for vt in the bios. Maybe I have done something wrong trying to configure EVC? I just checked the settings in vsphere client, and see something interesting. It reports an incompatible cpu for the 6850, but now it also reports one of my Precision 690's as also having an incompatible cpu. The other 690 seems fine. I think the two 690's are identical in bios settings, etc, so I'm not sure how to proceed with this. Any ideas?
Reply Re: Help with cpu id mask Jul 16, 2009 10:01 AM
in response to: jhp7395
Click to view AndreTheGiant's profile Guru AndreTheGiant 5,643 posts since
Aug 28, 2008
BIOS and BMC firmware are the latest?

Andre
Reply Re: Help with cpu id mask Jul 20, 2009 8:55 AM
in response to: AndreTheGiant
Click to view jhp7395's profile Novice jhp7395 13 posts since
Jun 8, 2006

Yes, both are the same. As far as I can tell both are identical, except for the amount of RAM. One has 20GB, but the other only has 4GB (haven't upgraded it yet), and that is the one that is not EVC compatible.
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