Hi Tim, I noticed you "Mask cmpxchg8b capability in cpuid for non-pae guests" in changeset 13107/13108: clear_bit(X86_FEATURE_CX8 & 31, edx). May I know the reason for the change?

We found an issue caused by the change: we can NOT install or boot 32bit HVM Windows 2003 guest on 32bit host. When we try to install 32bit HVM Windows 2003 guest on 32bit host, the windows installer complains: Windows requires certain processor features that are available on the processor in this computer. Specifically, Windows requires the following instructions. CPUID CMPXCHG8B Setup cannot continue. Press any key to exit.

Thanks! -- Dexuan