My Sparc 1+ running -current is hanging during boot:

timer0 at mainbus0 ioaddr 0xf3000000
auxreg0 at mainbus0 ioaddr 0xf7400003
zs0 at mainbus0 ioaddr 0xf1000000 pri 12, softpri 6
zs0a: console i/o
zs1 at mainbus0 ioaddr 0xf0000000 pri 12, softpri 6
audio0 at mainbus0 ioaddr 0xf7201000 pri 13, softpri 4
sbus0 at mainbus0 ioaddr 0xf8000000: clock = 20 MHz
dma0 at sbus0 slot 0 offset 0x400000: rev 1+
esp0 at sbus0 slot 0 offset 0x800000 pri 3: ESP100 20Mhz, target 7
scsibus0 at esp0
esp0 targ 3 lun 0: <SEAGATE, ST1480   SUN0424, 7516> SCSI2 0/direct fixed
sd0 at scsibus0: 411MB, 1476 cyl, 9 head, 63 sec, 512 bytes/sec
le0 at sbus0 slot 0 offset 0xc00000 pri 5: hardware address 08:00:20:0c:7d:b0
le1 at sbus0 slot 2 offset 0xc00000 pri 5: hardware address 08:00:20:0c:7d:b0
cgsix0 at sbus0 slot 3 offset 0x0: SUNW,501-1672, 1152 x 900, rev 6

At this point the keyboard lights flash, and nothing more happens.  I
feel like I've seen this before on my IPX, but I can't remember what
the problem is.