$ disklabel cd1
panic: todo(0) <= 0; minphys broken
Stopped in pid 1112.1 (disklabel) at netbsd:cpu_debugger+0x4: leave

panic: todo(%ld) <= 0; minphys broken
#0  0x00000000 in ?? ()
(gdb) bt
#0  0x00000000 in ?? ()
#1  0xc0ad5000 in ?? ()
#2  0xc046f9f1 in cpu_reboot (howto=260, bootstr=0x0)
     at /usr/src/sys/arch/i386/i386/machdep.c:752
#3  0xc0366011 in db_reboot_cmd (addr=1, have_addr=0, count=-1068051994,
     modif=0xce084a48 "@?\212?_J\b?\001") at /usr/src/sys/ddb/ 
db_command.c:694
#4  0xc0365b57 in db_command (last_cmdp=0xc08304e8,  
cmd_table=0xc06644a0)
     at /usr/src/sys/ddb/db_command.c:469
#5  0xc0365867 in db_command_loop () at /usr/src/sys/ddb/db_command.c: 
260
#6  0xc03689ab in db_trap (type=1, code=0) at /usr/src/sys/ddb/ 
db_trap.c:101
#7  0xc046cf2a in kdb_trap (type=1, code=0, regs=0xce084c9c)
     at /usr/src/sys/arch/i386/i386/db_interface.c:225
#8  0xc047a3e8 in trap (frame=0xce084c9c)
     at /usr/src/sys/arch/i386/i386/trap.c:270
#9  0xc010bdd2 in calltrap ()
#10 0xc03bb58d in panic (fmt=0xc07dbb80 "todo(%ld) <= 0; minphys  
broken")
     at /usr/src/sys/kern/subr_prf.c:228
#11 0xc039cd60 in physio (strategy=0xc0485b14 <cdstrategy>, bp=0x0,  
dev=3851,
     flags=1048576, min_phys=0xc04866b4 <cdminphys>, uio=0xce084eb4)
     at /usr/src/sys/kern/kern_physio.c:215
#12 0xc048674e in cdread (dev=3851, uio=0xce084eb4, ioflag=0)
     at /usr/src/sys/dev/scsipi/cd.c:1056
#13 0xc03f7266 in spec_read (v=0xce084e14)
     at /usr/src/sys/miscfs/specfs/spec_vnops.c:311
#14 0xc036422c in ufsspec_read (v=0xce084e14)
     at /usr/src/sys/ufs/ufs/ufs_vnops.c:1799
#15 0xc03f12d8 in VOP_READ (vp=0xcde87854, uio=0xce084eb4, ioflag=0,
     cred=0xcd1a0144) at /usr/src/sys/kern/vnode_if.c:458
#16 0xc03eeabc in vn_read (fp=0xcd1b7cd0, offset=0xce084f24,  
uio=0xce084eb4,
     cred=0xcd1a0144, flags=0) at /usr/src/sys/kern/vfs_vnops.c:455
#17 0xc03bf1ac in dofileread (p=0xce0168f4, fd=3, fp=0xcd1b7cd0,
     buf=0xbfbfe870, nbyte=512, offset=0xce084f24, flags=0,  
retval=0xce084f5c)
     at /usr/src/sys/kern/sys_generic.c:145
#18 0xc03eb2c2 in sys_pread (l=0xcd1abef4, v=0xce084f64,  
retval=0xce084f5c)
     at /usr/src/sys/kern/vfs_syscalls.c:1898
#19 0xc0479dad in syscall_plain (frame=0xce084fa8)
     at /usr/src/sys/arch/i386/i386/syscall.c:160