I'm probably going to have to chase this one down for myself, but before I do I figured I'd ask if anyone's seen anything similar before, and can give me some pointers...
When booting FreeBSD 9 under real SeaBIOS, it all works fine. When SeaBIOS is invoked for a 'legacy' boot under EFI, the FreeBSD bootloader gets as far as displaying its main screen with the FreeBSD banner and the ASCII-art dæmon and the options, but then seems to *stop* before displaying the 'Autoboot in 9 seconds. Press [Space] to pause' message.
The qemu log shows that it's in an endless stream of
Servicing hardware INT=0x20 44024: v=20 cr0=00000032 e=0000 i=0 cpl=0 IP=f000:000000000000ffec pc=00000000000fffec SP=0000:0000000000005d9c EAX=0000000000000000 EAX=00000000 EBX=00005dd0 ECX=0000ffea EDX=00000000 ESI=0000c350 EDI=00000000 EBP=00000000 ESP=00005d9c EIP=0000ffec EFL=00000202 [-------] CPL=0 II=0 A20=1 SMM=0 HLT=0 ES =d500 000d5000 ffffffff 00cf9300 CS =f000 000f0000 0000ffff 00009a00 SS =0000 00000000 ffffffff 00cf9300 DS =0000 00000000 ffffffff 00cf9300 FS =0000 00000000 ffffffff 00cff300 GS =0000 00000000 ffffffff 00cff300 LDT=0000 00000000 0000ffff 00008200 TR =0038 00005f98 00002067 00008900 GDT= 00009590 0000003f IDT= 00000000 000003ff CR0=00000032 CR2=00000000 CR3=7fb36000 CR4=00000648 DR0=0000000000000000 DR1=0000000000000000 DR2=0000000000000000 DR3=0000000000000000 DR6=00000000ffff0ff0 DR7=0000000000000400 CCS=00000044 CCD=00000000 CCO=EFLAGS EFER=0000000000000000 44025: v=1c cr0=00000032 e=0000 i=1 cpl=0 IP=f000:000000000000f856 pc=00000000000ff856 SP=0000:0000000000005d72 EAX=0000000000000000 EAX=00000000 EBX=00000000 ECX=00000000 EDX=00000000 ESI=00000000 EDI=00000000 EBP=00000000 ESP=00005d72 EIP=0000f856 EFL=00000202 [-------] CPL=0 II=0 A20=1 SMM=0 HLT=0 ES =0000 00000000 ffffffff 00cf9300 CS =f000 000f0000 0000ffff 00009a00 SS =0000 00000000 ffffffff 00cf9300 DS =0000 00000000 ffffffff 00cf9300 FS =0000 00000000 ffffffff 00cff300 GS =0000 00000000 ffffffff 00cff300 LDT=0000 00000000 0000ffff 00008200 TR =0038 00005f98 00002067 00008900 GDT= 00009590 0000003f IDT= 00000000 000003ff CR0=00000032 CR2=00000000 CR3=7fb36000 CR4=00000648 DR0=0000000000000000 DR1=0000000000000000 DR2=0000000000000000 DR3=0000000000000000 DR6=00000000ffff0ff0 DR7=0000000000000400 CCS=00000000 CCD=00000000 CCO=EFLAGS EFER=0000000000000000 Servicing hardware INT=0x20