On the odd chance this is of help to anyone...

  Just updated my 2.0_RC5 system to 2.0 with build.sh as per normal
procedure, installed kernel, rebooted and installed the distribution to /
and rebooted, and all seemed fine. Then I realized I should probably build
a release while I was at it, for burning a CD to bring home. To avoid
rebuilding the entire system I did a build.sh -u -M [....] tools release.
Checking back this afternoon I find the machine has:

db> bt
uvm_anfree(603c228, 11bc400, 1c68bf0, 8000000010784632, ffffffffffffffff, 1810000) at netbsd:uvm_anfree+0xb8
amap_wipeout(603c220, 0, 9, 0, 3fffff, 11cac00) at netbsd:amap_wipeout+0xf8
uvm_unmap_detach(6091e90, 0, ffffffffffffffff, 5ed7ae8, 13f, ed2) at netbsd:uvm_unmap_detach+0x160
uvmspace_free(6445740, 0, 0, 1, badcafe, badcafe) at netbsd:uvmspace_free+0xe0
exit1(6460710, 0, 40222180, ffffffffffffce68, 1, 12) at netbsd:exit1+0x308
sys_exit(0, 5ed7dd0, 5ed7dc0, 1, 9182008202, 0) at netbsd:sys_exit+0x3c
syscall(5ed7ed0, 1, 409310ec, 800, 1814800, 0) at netbsd:syscall+0x32c
?(0, 0, 11d400, 220400, 4, 1) at 0x1009614

and:

db> ps
 PID           PPID     PGRP        UID S   FLAGS LWPS          COMMAND    WAIT
>23592        14670     1484          0 2  0x6002    1               sh
 14670         1681     1484          0 2  0x4002    1           nbmake    wait
 1681         23999     1484          0 2  0x4002    1               sh    wait
 23999        14701     1484          0 2  0x4002    1           nbmake    wait
 14701        11820     1484          0 2  0x4002    1               sh    wait
 11820         4132     1484          0 2  0x4002    1           nbmake    wait
 4132         25721     1484          0 2  0x4002    1               sh    wait
 25721         3698     1484          0 2  0x4002    1           nbmake    wait
 3698         27792     1484          0 2  0x4002    1               sh    wait
 27792        27941     1484          0 2  0x4002    1           nbmake    wait
 27941        18746     1484          0 2  0x4002    1               sh    wait
 18746         1484     1484          0 2  0x4002    1           nbmake    wait
 1484           304     1484          0 2  0x5002    1               sh    wait
 303             70       70       1000 2   0x100    1            httpd  netcon
 350             70       70       1000 2   0x100    1            httpd  netcon
 415             70       70       1000 2   0x100    1            httpd  netcon
 397             70       70       1000 2   0x100    1            httpd  netcon
 392             70       70       1000 2   0x100    1            httpd  netcon
 369             70       70       1000 2   0x100    1            httpd  netcon
 297             70       70       1000 2   0x100    1            httpd  netcon
 284             70       70       1000 2   0x100    1            httpd  netcon
 302            307       70       1000 2  0x4000    1             perl  netcon
 307             70       70       1000 2   0x100    1            httpd  select
 70               1       70          0 2       0    1            httpd  select
 304              1      304          0 2  0x4003    1              ksh   ttyin
 310              1      310          0 2       0    1             cron nanosle
 317              1      317          0 2       0    1            inetd  kqread
 298              1      298          8 2   0x100    1      exim-4.42-1  select
 263              1      263          0 2       0    1             sshd  select
 148              1      148         14 2   0x100    1            named  select
 120              1      120          0 2       0    1          syslogd
 5                0        0          0 2 0x20200    1         aiodoned aiodone
 4                0        0          0 2 0x20200    1          ioflush  syncer
 3                0        0          0 2 0x20200    1       pagedaemon pgdaemo
 2                0        0          0 2 0x20200    1         scsibus0  sccomp
 1                0        1          0 2  0x4000    1             init    wait
 0               -1        0          0 2 0x20200    1          swapper

Unfortunately, I don't have the original panic message that would
have preceeded the "db>" prompt, because I wasn't logged in at the machine
acting as serial console for this machine at the time (and the machine
doesn't have screen(1) installed a.t.m).

Rebooting from the db> prompt works a lot better than during pthread
("ltsleep)" panics and I got some gcc/make output when I did it:

db> reboot
syncing disks... hme0: status=30003<GOTFRAME,RCNTEXP,RXTOHOST,NORXD>
e.
`inode.o' is up to date.
`main.
switching with held simple_lock 0x603c228 CPU 0
/usr/src/sys/uvm/uvm_anon.c:242

switching with held simple_lock 0x603c228 CPU 0
/usr/src/sys/uvm/uvm_anon.c:242
o' is up to date.
`pass1.o' is up to date.
`pass1b.o' is up to date.
`pass2.o' is up to date.
`pass3.o' i
switching with held simple_lock 0x603c228 CPU 0
/usr/src/sys/uvm/uvm_anon.c:242
s up to date.
`pass4.o' is up to date.
`pass5.o' is up to date.
`fsutil.o' is up to date.
`setup.o' is up to date.
`utilities.o
switching with held simple_lock 0x603c228 CPU 0
/usr/src/sys/uvm/uvm_anon.c:242
' is up to date.
`ext2fs_bswap.o' 2
switching with held simple_lock 0x603c228 CPU 0
/usr/src/sys/uvm/uvm_anon.c:242
is up1
switching with held simple_lock 0x603c228 CPU 0
/usr/src/sys/uvm/uvm_anon.c:242
 to date.
done
unmounting /kern (kernfs)...
unmounting /local (/dev/sd1a)...

...followed by a lot more of

switching with held simple_lock 0x603c228 CPU 0 /usr/src/sys/uvm/uvm_anon.c:242

Anyone know what caused this fatal failure?

-- 
/ali
:wq