dmesg won't pull message buffer from core on x86

[Craig Metz <cmetz_(_at_)_inner_(_dot_)_net>]

  On my x86 development boxen [running 2.3], when I dump a core and try to pull
the message buffer back to see what printf()s fired, I get:

>jimbo# ./dmesg -N /var/crash/bsd.1 -M /var/crash/bsd.1.core
>dmesg: kvm_read: 

  Which isn't a particularly helpful error message. ktrace doesn't yield any
obvious explanations, either (this is the tail end):

 13597 dmesg    CALL  munmap(0x400bb0c4,0x6b12e9)
 13597 dmesg    RET   munmap 0
 13597 dmesg    CALL  lseek(0x7,0,0x21f868,0,0)
 13597 dmesg    RET   lseek 2226280/0x21f868
 13597 dmesg    CALL  read(0x7,0xefbfcb18,0x4)
 13597 dmesg    GIO   fd 7 read 4 bytes
       "c\240!\0"
 13597 dmesg    RET   read 4
 13597 dmesg    CALL  lseek(0x7,0,0x21a400,0,0)
 13597 dmesg    RET   lseek 2204672/0x21a400
 13597 dmesg    CALL  read(0x7,0xefbfcb74,0x4)
 13597 dmesg    GIO   fd 7 read 4 bytes
       "\0\^P,\M-p"
 13597 dmesg    RET   read 4
 13597 dmesg    CALL  lseek(0x7,0,0x21fb04,0,0)
 13597 dmesg    RET   lseek 2226948/0x21fb04
 13597 dmesg    CALL  read(0x7,0xefbfcb18,0x4)
 13597 dmesg    GIO   fd 7 read 4 bytes
       "c\M-r\M^?\^C"
 13597 dmesg    RET   read 4
 13597 dmesg    CALL  lseek(0x7,0,0x3fff000,0,0)
 13597 dmesg    RET   lseek 67104768/0x3fff000
 13597 dmesg    CALL  read(0x7,0xefbfcb80,0x1000)
 13597 dmesg    GIO   fd 7 read 0 bytes
       ""
 13597 dmesg    RET   read 0
 13597 dmesg    CALL  write(0x2,0xefbfc3a4,0x7)
 13597 dmesg    GIO   fd 2 wrote 7 bytes
       "dmesg: "
 13597 dmesg    RET   write 7
 13597 dmesg    CALL  write(0x2,0xefbfc3bc,0xa)
 13597 dmesg    GIO   fd 2 wrote 10 bytes
       "kvm_read: "
 13597 dmesg    RET   write 10/0xa
 13597 dmesg    CALL  write(0x2,0xefbfc3a8,0x1)
 13597 dmesg    GIO   fd 2 wrote 1 bytes
       "
       "
 13597 dmesg    RET   write 1
 13597 dmesg    CALL  exit(0x1)

  dmesg(8) appears to be the same between 2.3 and the current CVS version.

  Any suggestions as to how to proceed? I can always use strings to get at the
messages, but it's a painful way to do it.

								  -Craig