timecounter changes break netbsd-9/i386 for NET4501

["John D. Baker" <jdbaker%consolidated.net@localhost>]

After updating with the latest pull-ups to netbsd-9, my Soekris net4501
panics during boot with:

[   1.0000000] Copyright (c) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
[   1.0000000]     2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017,
[   1.0000000]     2018, 2019, 2020 The NetBSD Foundation, Inc.  All rights reserved.
[   1.0000000] Copyright (c) 1982, 1986, 1989, 1991, 1993
[   1.0000000]     The Regents of the University of California.  All rights reserved.

[   1.0000000] NetBSD 9.0_STABLE (NET4501_JDB) #79: Sat Jul 18 08:19:53 CDT 2020
[   1.0000000] 	sysop%plex760.technoskunk.fur@localhost:/r0/build/netbsd-9/obj/i386/sys/arch/i386/compile/NET4501_JDB
[   1.0000000] total memory = 65148 KB
[   1.0000000] avail memory = 60628 KB
[   1.0000050] mainbus0 (root)
[   1.0000050] cpu0 at mainbus0
[   1.0000050] fatal privileged instruction fault in supervisor mode
[   1.0000050] trap type 0 code 0 eip 0xc0114c30 cs 0xc0430008 eflags 0x10246 cr2 0 ilevel 0x8 esp 0xc011f0cb
[   1.0000050] curlwp 0xc0351960 pid 0 lid 1 lowest kstack 0xc04342c0
kernel: supervisor trap privileged instruction fault, code=0
Stopped in pid 0.1 (system) at  netbsd:cpu_counter:     rdtsc
db{0}> bt
cpu_counter(c034c680,c034c950,c0435ef4,c0435e5c,c011f3ab,c034c680,c034c680,c034c
950,1008,c0435ef4) at netbsd:cpu_counter
cpu_get_tsc_freq(c034c680,c034c680,c034c950,1008,c0435ef4,c05fe340,24,0,c05fe340
,c05fe340) at netbsd:cpu_get_tsc_freq+0x32
cpu_attach(c05fe1c0,c05fe340,c0435ef4,c05fe340,c0435ef4,c02d9b7b,c0435ef4,c05fe1
c0,c011c87d,c0435eb8) at netbsd:cpu_attach+0x2a7
config_attach_loc(c05fe1c0,c0354fd0,0,c0435ef4,c011c87d,c05fe1c0,9fc00,c05fe1c0,
c03550a8,c0435f04) at netbsd:config_attach_loc+0x14a
config_found_sm_loc(c05fe1c0,c02da3bf,0,c0435ef4,c011c87d,0,c0435f0c,c011c90d,c0
5fe1c0,c02da3bf) at netbsd:config_found_sm_loc+0x35
config_found_ia(c05fe1c0,c02da3bf,c0435ef4,c011c87d,0,0,0,0,0,c05fe1c0) at netbs
d:config_found_ia+0x18
mainbus_attach(0,c05fe1c0,0,c05fe1c0,0,c02d9097,c02d9097,0,439000,c0435f54) at n
etbsd:mainbus_attach+0x6e
config_attach_loc(0,c0355018,0,0,0,c0435f74,c023c468,0,c0355018,0) at netbsd:con
fig_attach_loc+0x14a
config_attach(0,c0355018,0,0,c043300c,433000,c0435f84,c0114751,c02d9097,0) at ne
tbsd:config_attach+0x16
config_rootfound(c02d9097,0,c0435fb0,c02c4459,0,0,0,0,0,ffff) at netbsd:config_r
ootfound+0x26
cpu_configure(0,0,0,0,0,ffff,c043300c,433000,439000,0) at netbsd:cpu_configure+0
x28
main(0,0,0,0,0,0,0,0,0,0) at netbsd:main+0x233


ISTR something similar happened a few years ago with an improperly
safeguarded "rdtsc" instruction which the CPU in the net4501 doesn't
support (IIRC).

Fortunately, I was able to switch to my previous kernel (from just over
a month ago) and resume operation.

-- 
|/"\ John D. Baker, KN5UKS               NetBSD     Darwin/MacOS X
|\ / jdbaker[snail]consolidated[flyspeck]net  OpenBSD            FreeBSD
| X  No HTML/proprietary data in email.   BSD just sits there and works!
|/ \ GPGkeyID:  D703 4A7E 479F 63F8 D3F4  BD99 9572 8F23 E4AD 1645