Does sparse_dump work on amd64?

[Paul Goyette <paul%whooppee.com@localhost>]

My amd64 machine crashed (twice) yesterday while I was out, and it seems 
to have not completely dumped everything into /var/crash

-rw-------  1 root  wheel      588450 Apr 28 01:10 netbsd.3
-rw-------  1 root  wheel  1158063640 Apr 28 01:10 netbsd.3.core
-rw-------  1 root  wheel           0 Jun 28 09:16 netbsd.4
-rw-------  1 root  wheel  5618551832 Jun 28 09:16 netbsd.4.core

The kernel images are obviously not valid, given that my real kernel is 
10 times larger than netbsd.3 ...

-rwxrwxr-x  1 root  wheel   5475042 Feb 22 13:36 /netbsd
-rwxr-xr-x  1 root  wheel  29566097 Feb 22 13:36 /netbsd.gdb

Anyway, when I look at the core files with gdb, the netbsd.4.core file 
seems to be invalid:

(gdb) target kvm netbsd.4.core
Cannot access memory at address 0x68d775f0
(gdb) bt
#0  <unavailable> in ?? ()
Backtrace stopped: Not enough registers or memory available to unwind 
further
(gdb)


FWIW, the netbsd.3.core dump does seem to have valid info.  But I don't 
have a clue why the machine would have tried to trap:

(gdb) target kvm netbsd.3.core
#0  0xffffffff8021d91e in ?? ()
(gdb) file /netbsd.gdb
Reading symbols from /netbsd.gdb...done.
(gdb) bt
#0  0xffffffff8021d91e in cpu_reboot (howto=260, bootstr=<optimized out>)
    at /build/netbsd-local/src/sys/arch/amd64/amd64/machdep.c:779
#1  0xffffffff802ce686 in vpanic (fmt=0xffffffff80408e9c "trap",
    ap=0xfffffe813b5d0240) at /build/netbsd-local/src/sys/kern/subr_prf.c:284
#2  0xffffffff802ce73a in panic (fmt=<unavailable>)
    at /build/netbsd-local/src/sys/kern/subr_prf.c:200
#3  0xffffffff8030012d in trap (frame=0xfffffe813b5d0380)
    at /build/netbsd-local/src/sys/arch/amd64/amd64/trap.c:294
#4  0xffffffff80100f66 in calltrap ()
#5  0xffff80003f7a1000 in ?? ()
#6  0xffff80003f7a3030 in ?? ()
#7  0x00000000000003c0 in ?? ()
#8  0x0000000000000000 in ?? ()



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