[Xen-users] Re: Xen-users Digest, Vol 47, Issue 188

[PattiMichelle <miche1@xxxxxxxxxxxxx>]

Yes, thank you James, that's about right, but domU seems to see all cores, it's just the guest OS that sees only one core-per-socket.  To overcome that, I'd like to convert all sockets (in the guest) to dual or quad cores (AMD).  I found the guest's config file, not sure where the domU config file is.

I bought, but didn't find any references to this subject in the book "Running Xen."  I was confused by the position within the string of "xxxx"-s of the apparently binary information in those structure variables - is position important?  Now it's even more complicated since AMDs are treated differently than Intel!  Thank you for the cut-n-paste - I guess I can try fooling around with it and see if I get lucky, else one of the Xen authors can help?

Now that I think about it, can I run WinXP and expose two 16-core processors? (XP is supposed to support two sockets).  That would be bonus.
Patti

If I understand what you want correctly, you can do this by specifying
the cpuid option in your domU config. The following is cut&paste from
xmexample.hvm

# Expose to the guest multi-core cpu instead of multiple processors
# Example for intel, expose a 8-core processor :
#cpuid=['1:edx=xxx1xxxxxxxxxxxxxxxxxxxxxxxxxxxx,
#          ebx=xxxxxxxx00010000xxxxxxxxxxxxxxxx',
#     '4,0:eax=001111xxxxxxxxxxxxxxxxxxxxxxxxxx']
#  - CPUID.1[EDX][HT] : Enable HT
#  - CPUID.1[EBX] : Number of vcpus * 2
#  - CPUID.4,0[EAX] : Number of vcpus * 2 - 1
#vcpus=8
#
# Example for amd, expose a 5-core processor :
# cpuid = ['1:ebx=xxxxxxxx00001010xxxxxxxxxxxxxxxx,
#             edx=xxx1xxxxxxxxxxxxxxxxxxxxxxxxxxxx',
# '0x80000001:ecx=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx1x',
# '0x80000008:ecx=xxxxxxxxxxxxxxxxxxxxxxxxxx001001']
#   - CPUID.1[EBX] : Threads per Core * Cores per Socket (2 * #vcpus)
#   - CPUID.1[EDX][HT] : Enable HT
#   - CPUID.0x80000001[CmpLegacy] : Use legacy method
#   - CPUID.0x80000008[ECX] : #vcpus * 2 - 1
#vcpus=5

I'm not sure what version of xen you get with OpenSuse 11, and I'm not
exactly sure when the cpuid option first appeared.

James



  

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