Thanks for the articles Scott, they helped out. Here's how I managed to get Vmotion working on my test system.
Trying to perform a Vmotion from a Dell 2950 to a Dell 2850 (fyi: according to the Dell chart here: http://download3.vmware.com/vmworld/2006/tac1356.pdf they are incompatible with VMotion).
Dell 2950 with 2 Intel(R) Xeon(R) CPU 5160 @ 3.00Ghz
Dell 2850 with 2 Intel(R) Xeon(TM) CPU 3.60Ghz
When attempting to perform the VMotion, I would see the following message:
The CPU of the host is incompatible with the CPU feature requirements of virtual machine; problem detected at CPUID level 0x1 register 'eax'.[/b]
First, I downloaded the VMotion Info utility (http://www.run-virtual.com/?page_id=155). The trick is to run it in debug mode (there is a option on the login page for this) so you can see the actual registers:
For the 2850 CPU 0 Level 1, eax register:
0000:0000:0000:0000:0000:1111:0100:0011
For the 2950 CPU 0 Level 1, eax register:
0000:0000:0000:0000:0000:0110:1111:0110
The different bits are:
0000:0000:0000:0000:0000:\*11*:*1**:0*1*
Then on the VM, Edit Settings...Options Tab...Advanced...Advanced Button. Click on Level 1 eax. The default mask for the EAX row (shown in the Row details section):
XXXX HHHH HHHH XXXX XXXX HHHH XXXX XXXX
X bits are not used by the VM, the H bits are shown to the VM, so basically we can ignore any different bits that have an X. To disable the feature, we want to set the conflicting bits to 0. The resulting bit mask is:
\-- -
-
-
-
00 -
-
XXXX HHHH HHHH XXXX XXXX 0HH0 XXXX XXXX
After saving the changes and attempting to VMotion again, I would see the following message:
The CPU of the host is incompatible with the CPU feature requirements of virtual machine; problem detected at CPUID level 0x1 register 'ecx'.[/b]
Checking the VMotion Info Utility for the ecx register differences:
For the 2850 CPU 0 Level 1, ecx register:
0000:0000:0000:0000:0110:0101:1001:1101
For the 2950 CPU 0 Level 1, ecx register:
0000:0000:0000:0100:1110:0011:1011:1101
The different bits are:
0000:0000:0000:0*00:*110:0**1:1011:1101
The default mask for the ECX register (again, click on the register and see the default in the Row details section below):
RRRR RRRR RRRR RRR0 00XR R0H0 000H 0RRH
R bits are already hidden from the OS, X bits are not used by the VM, and the 0 bits are already hidden, so we only need to mask out the conflicting H bits with a zero:
\-- -
-
-0 -
--0- -
-
RRRR RRRR RRRR R0R0 00XR R000 000H 0RRH
After saving the changes and attempting to VMotion again, it works! Well it seems to work anyway. The trick now is to figure out if I'm worried that making VMotion ignore those bits is going to cause me problems later on. I'm probably guessing that it will cause me problems, so I won't do this on my production environment. Fun to do in testing though.
For the EAX register, I changed bits 8 & 11 (the processor family identifier bits).
For the ECX register, I changed bits:
9 - SSSE3 (Which is what VMotion Info found as incompatible)
18 - DCA (Direct Cache Access)
