Aha! Caught one... (compile lynx 2.5, NetBSD kernel and CVS on an
8Mb machine with three xterm displayed on another machine). Then type 
'man ktrace' on the console.
  (What programs do I need to recompile after 1.2B??? AMD I got, but i
thought that mount_nfs would it after 'make install' in
/usr/src/include. Is src/include part of ksrc??? This is for a
NetBSD/i486) 

ktrace.0 (70%)Breakpoint at   _trapsignal:    linkw   a6,#0
db> trace
_trapsignal(1,f041,616c2025) + 0
sun3_mmu_specific() + 38
db> 

  blunders around in kern/kern_sig.c... but I'm confused as to what happens.
  ARGH. NOW WHAT? 
  Wait... arg #2 is "signum" --- shouldn't this be 1-32?  Arg #3 is a
signal specific code, right?

  Here for fun, Gordon is the result of me mucking around in DBD a
bit: I'm afraid the rest has scrolled off. I will now pop into script
first...

db> trace
_trapsignal(?)
_trap(1,f041,616c2025) + d4
sun3_mmu_specific() + 38
db> s
Stopped at      _trap+0x498:    addqw   #0x8,sp
db> s
Stopped at      _trap+0x49a:    addqw   #0x4,sp
db> s
Stopped at      _trap+0x49c:    movl    a6@(-0x4),sp@-
db> s
Stopped at      _trap+0x4a0:    movl    a6@(-0x8),sp@-
db> s
Stopped at      _trap+0x4a4:    pea     a6@(0x14)
db> s
Stopped at      _trap+0x4a8:    movl    a2,sp@-
db> s
Stopped at      _trap+0x4aa:    bsrw    _userret        [addr:0xe09c3a6 ]
db> s
Stopped at      _userret:       linkw   a6,#0
db> s
Stopped at      _userret+0x4:   movml   d2/a2-a3,sp@-
db> s
Stopped at      _userret+0x8:   moval   a6@(0x8),a2
db> s
Stopped at      _userret+0xc:   moval   a6@(0xc),a3
db> s
Stopped at      _userret+0x10:  tstl    a2@(0xb0)
db> 
Stopped at      _userret+0x14:  beqb    <_userret+0x36> [addr:0xe09c3dc ]
db> 
Stopped at      _userret+0x16:  btst    #0x3,a2@(0x2a)
db> 
Stopped at      _userret+0x1c:  bneb    <_userret+0x2a> [addr:0xe09c3d0 ]
db> 
Stopped at      _userret+0x1e:  movl    a2@(0xc4),d0
db> 
Stopped at      _userret+0x22:  notl    d0
db> 
Stopped at      _userret+0x24:  andl    a2@(0xb0),d0
db> 
Stopped at      _userret+0x28:  beqb    <_userret+0x36> [addr:0xe09c3dc ]
db> 
Stopped at      _userret+0x2a:  movl    a2,sp@-
db> 
Stopped at      _userret+0x2c:  bsrl    _issignal       [addr:0xe01636c ]
db> 
Stopped at      _issignal:      linkw   a6,#0
db> 
Stopped at      _issignal+0x4:  movml   d2-d4/a2,sp@-
db> 
Stopped at      _issignal+0x8:  moval   a6@(0x8),a2
db> 
Stopped at      _issignal+0xc:  movl    a2@(0xc4),d0
db> 
Stopped at      _issignal+0x10: notl    d0
db> 
Stopped at      _issignal+0x12: movl    d0,d1
db> 
Stopped at      _issignal+0x14: andl    a2@(0xb0),d1
db> 
Stopped at      _issignal+0x18: btst    #0x4,a2@(0x2b)
db> 



   :!mcr!:            |  Cow#1: Are you worried about getting Mad Cow Disease?
   Michael Richardson |  Cow#2: No. I'm a duck.
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