I have been fighting for quite some time to get Solaris 10 installed and working properly under VMwae Fusion 1.1 on an Intel Core 2 Duo Mac. I think this is an interaction problem between VMware Fusion and Solaris 10. Even if you tell VMware Fusion that you want to install Solaris in 32-bit mode, VMware doesn’t disable the 64-bit, long-word instruction support (available from the host). Thus, Solaris 10 is able to detect that 64-bit, long-word instructions are available and boots a 64-bit kernel. VMware then complains about the fact that the virtual machine was configured in 32-bit mode but the guest is trying to execute 64-bit instructions.

The work-around is pretty easy: it consists of disabling 64-bit, long-word instructions in the VMware configuration file for the guest. This is described in greater detail in article Installing Solaris 10 as a 32-Bit Guest Operating System on a 64-Bit Host Machine but consists mainly in editing the .vmx virtual machine’s configuration file and adding the following line:

monitor_control.disable_longmode = 1

Rebooting the installation, or booting an already installed virtual machine system should make Solaris boot into 32-bit mode.