Panic seen on 19990406 snapshot using the GENERIC kernel. System is:
[...]
mainbus0 (root): SUNW,SPARCstation-10
cpu0 at mainbus0: TMS390Z50 v0 or TMS390Z55 @ 50 MHz, on-chip FPU
cpu0: physical 20K instruction (64 b/l), 16K data (32 b/l), 1024K external (32 b/l): cache enabled
cpu at mainbus0 not configured
[...]

Was compiling the world and saw this partway through:

data fault: pc=0xf000a33c addr=0xf02c6ff8 sfsr=3a6<PERR=0,LVL=3,AT=5,FT=1,FAV,OW>
panic: kernel fault
syncing disks... 8 8 5 1 done
Frame pointer is at 0xf4714a28
Call traceback:
  pc = 0xf01ad784  args = (0x409000e3, 0x40900fe3, 0x0, 0x0, 0xf4714b40, 0x409000e3, 0xf4714a90) fp = 0xf4714a90
  pc = 0xf005df40  args = (0x100, 0x0, 0x0, 0x0, 0xf4714bb4, 0x409000e4, 0xf4714af8) fp = 0xf4714af8
  pc = 0xf01bd860  args = (0xf01bcf60, 0x100, 0xf02c6ff8, 0xf4714bc0, 0x1e, 0xf0216800, 0xf4714b60) fp = 0xf4714b60
  pc = 0xf0008518  args = (0x0, 0x3a6, 0xf02c6ff8, 0xf4714c68, 0x0, 0x1, 0xf4714c08) fp = 0xf4714c08
  pc = 0xf01bb134  args = (0xf02c6000, 0xff8, 0xf0285f18, 0xf01e4000, 0x8aef9e, 0xf0002000, 0xf4714cb8) fp = 0xf4714cb8
  pc = 0xf014c5fc  args = (0x8aef000, 0x210, 0xf021bc00, 0xf01bb08c, 0xf0225000, 0x0, 0xf4714d20) fp = 0xf4714d20
  pc = 0xf0146378  args = (0xf041e120, 0x1e755, 0xf0216988, 0x0, 0x0, 0x75000, 0xf4714d88) fp = 0xf4714d88
  pc = 0xf01bd770  args = (0xf041e120, 0x5, 0x7, 0xffffffff, 0xf47074e0, 0xf0216800, 0xf4714ea8) fp = 0xf4714ea8
  pc = 0xf0008518  args = (0xf45eadc0, 0x386, 0x75004, 0xf4714fb0, 0x72008, 0x0, 0xf4714f50) fp = 0xf4714f50
  pc = 0xc8dc  args = (0x3ff, 0x400, 0xa, 0x200, 0x75004, 0x76000, 0xeffff698) fp = 0xeffff698

dumping to dev 7,1 offset 133423
dump 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 succeeded
rebooting



Jon