Ah okay. What does that change to scsi_options actually *do*?
From glancing at the include file (usr/src/uts/sys/scsi/conf/autoconf.h, should be in the exported opensolaris), the bits 0x58 enable:
- Global disconnect/reconnect - Global Linked Commands - Global Parity Support
Notably it does *not* include global synchronous transfer capability, tagged command support or any of the fast/wide possibilities. I can't find where the default scsi_options are for the esp driver, but presumably it had some of those capabilities enabled, which aren't supported by the qemu scsi driver.