Building your own kernel (on your fast machine with lots of memory), stripped of every driver your machine doesn't have, can get you a bit further on memory constrained machines. This gets you into unsupported land, but if you want support you're probably best of spending a nickel and getting a better computer.
I jumped through several hoops to get this going on an ancient machine (an HP Vectra N2 4/33si) half a year ago and got this: OpenBSD 6.0-current (REALSMALL) #0: Tue Feb 14 16:20:40 CET 2017 we...@i386.alm.weirdnet.nl:/usr/src/sys/arch/i386/compile/REALSMALL cpu0: Intel 486DX2 ("GenuineIntel" 486-class) cpu0: FPU,V86 real mem = 16314368 (15MB) avail mem = 12226560 (11MB) warning: no entropy supplied by boot loader mainbus0 at root bios0 at mainbus0: date 10/21/94 apm0 at bios0: Power Management spec V1.0 apm0: APM get power status: unrecognized device ID (9) bios0: ROM list: 0xc0000/0x8000 cpu0 at mainbus0: (uniprocessor) isa0 at mainbus0 isadma0 at isa0 fdc0 at isa0 port 0x3f0/6 irq 6 drq 2 fd0 at fdc0 drive 0: 1.44MB 80 cyl, 2 head, 18 sec com0 at isa0 port 0x3f8/8 irq 4: ns16550a, 16 byte fifo com1 at isa0 port 0x2f8/8 irq 3: ns16550a, 16 byte fifo pckbc0 at isa0 port 0x60/5 irq 1 irq 12 pckbd0 at pckbc0 (kbd slot) wskbd0 at pckbd0: console keyboard vga0 at isa0 port 0x3b0/48 iomem 0xa0000/131072 wsdisplay0 at vga0 mux 1: console (80x25, vt100 emulation), using wskbd0 wsdisplay0: screen 1-5 added (80x25, vt100 emulation) wdc0 at isa0 port 0x1f0/8 irq 14 wd0 at wdc0 channel 0 drive 0: <QUANTUM LPS210A> wd0: 8-sector PIO, CHS, 201MB, 723 cyl, 15 head, 38 sec, 412110 sectors wd0(wdc0:0:0): using BIOS timings ep0 at isa0 port 0x300/16: address 00:20:af:56:38:50, aui/bnc (default aui) ep1 at isa0 port 0x210/16: address 00:20:af:b5:1a:d4, utp/aui/bnc (default utp) pcppi0 at isa0 port 0x61 spkr0 at pcppi0 npx0 at isa0 port 0xf0/16: reported by CPUID; using exception 16 softraid0 at root scsibus0 at softraid0: 256 targets root on wd0a (29c2d8b7afeebf3a.a) swap on wd0b dump on wd0b Sadly, the disk was too small (at 200MB) to properly install OpenBSD, so I trashed the machine. But, as can be seen, this machine did support CPUID! Cheers, Paul 'WEiRD' de Weerd On Fri, Sep 01, 2017 at 10:27:11AM +0200, Janne Johansson wrote: | A few quick tests on 6.1-i386 in a VM showed that 20M seems to be minimum | now, at 17-19M disk setup would segfault late in the installation and at | 16M em0 couldn't get TX stuff allocated, so that failed even earlier. | | | 2017-09-01 9:43 GMT+02:00 Mike Larkin <mlar...@azathoth.net>: | | > On Thu, Aug 31, 2017 at 11:57:40PM -0700, Mike Larkin wrote: | > > On Fri, Sep 01, 2017 at 01:04:40AM -0500, Andrew Daugherity wrote: | > > > I recently dug out of the closet my old IBM PS/2E, which had served as | > > > my firewall box from 2000ish-06, and was in fact the very first | > > > machine I ever installed OpenBSD on, to see if it still worked | > > > properly. It did (after changing the CMOS battery), but booted into | > > > OpenBSD 4.1... yeah, just a *bit* out of date there. The machine may | > > > not be of great use nowadays (I'd retired it when it couldn't keep up | > > > with my internet connection), but even as a retro-computing | > > > playground, running a 10-year-old/20-releases-ago version of OpenBSD | > > > is of no benefit. Let's rectify that! | > > > | > > > ==== | > > > >> OpenBSD/i386 BOOT 3.31 | > > > boot> hd0a:/bsd61.rd | > > > cannot open hd0a:/etc/random.seed: No such file or directory | > > > booting hd0a:/bsd61.rd: 3208120+1332224+3342348+0+446464 | > > > [72+288736+277711]=0x87e694 | > > > entry point at 0x2000d4 | > > > | > > > Copyright (c) 1982, 1986, 1989, 1991, 1993 | > > > The Regents of the University of California. All rights | > reserved. | > > > Copyright (c) 1995-2017 OpenBSD. All rights reserved. | > https://www.OpenBSD.org | > > > | > > > OpenBSD 6.1 (RAMDISK_CD) #289: Sat Apr 1 13:58:25 MDT 2017 | > > > dera...@i386.openbsd.org:/usr/src/sys/arch/i386/compile/RAMDISK_CD | > > > fatal privileged instruction fault (0) in supervisor mode | > > > trap type 0 code 0 eip d03b1f7c cs d09f0008 eflags 10046 cr2 0 cpl 0 | > > > panic: trap type 0, code=0, pc=d03b1f7c | > > > | > > > The operating system has halted. | > > > Please press any key to reboot. | > > > ==== | > > > | > > > Well, that's not good -- I didn't expect 6.1 to run particularly well | > > > on this, but I figured it would at least boot... how about 6.0? | > > > | > > > | > > > ==== | > > > booting hd0a:/bsd60.rd: 3211188+1318224+2061312+0+442368 | > > > [72+298576+282894]=0x744144 | > > > entry point at 0x2000d4 | > > > | > > > Copyright (c) 1982, 1986, 1989, 1991, 1993 | > > > The Regents of the University of California. All rights | > reserved. | > > > Copyright (c) 1995-2016 OpenBSD. All rights reserved. | > http://www.OpenBSD.org | > > > | > > > OpenBSD 6.0 (RAMDISK_CD) #1864: Tue Jul 26 12:57:09 MDT 2016 | > > > dera...@i386.openbsd.org:/usr/src/sys/arch/i386/compile/RAMDISK_CD | > > > cpu0: Intel 486DX (486-class) | > > > real mem = 16183296 (15MB) | > > > avail mem = 8122368 (7MB) | > > > mainbus0 at root | > > > bios0 at mainbus0: date 03/31/93 | > > > pcibios at bios0 function 0x1a not configured | > > > bios0: ROM list: 0xc8000/0x1000 0xc9000/0x1000 0xca000/0x2000 | > > > cpu0 at mainbus0: (uniprocessor) | > > > isa0 at mainbus0 | > > > isadma0 at isa0 | > > > fdc0 at isa0 port 0x3f0/6 irq 6 drq 2 | > > > fd0 at fdc0 drive 0: 1.44MB 80 cyl, 2 head, 18 sec | > > > com0 at isa0 port 0x3f8/8 irq 4: ns16450, no fifo | > > > com0: console | > > > pckbc0 at isa0 port 0x60/5 irq 1 irq 12 | > > > pckbd0 at pckbc0 (kbd slot) | > > > wskbd0 at pckbd0: console keyboard | > > > vga0 at isa0 port 0x3b0/48 iomem 0xa0000/131072 | > > > wsdisplay0 at vga0 mux 1: console (80x25, vt100 emulation), using | > wskbd0 | > > > wdc0 at isa0 port 0x1f0/8 irq 14 | > > > wd0 at wdc0 channel 0 drive 0: <IBM-DARA-206000> | > > > wd0: 16-sector PIO, LBA, 5729MB, 11733120 sectors | > > > wd0(wdc0:0:0): using BIOS timings | > > > npx0 at isa0 port 0xf0/16 irq 13 | > > > pcic0 at isa0 port 0x3e0/2 iomem 0xd0000/16384 | > > > pcic0 controller 0: <Intel 82365SL rev 1> has sockets A and B | > > > pcic0 controller 1: <Intel 82365SL rev 1> has sockets A and B | > > > pcmcia0 at pcic0 controller 0 socket 0 | > > > pcmcia1 at pcic0 controller 0 socket 1 | > > > pcmcia2 at pcic0 controller 1 socket 0 | > > > ep1 at pcmcia2 function 0 "3Com, 3C574-TX Fast EtherLink PC Card, A" | > > > port 0x340/32, irq 3: address 00:10:4b:5f:20:c0 | > > > tqphy0 at ep1 phy 0: 78Q2120 10/100 PHY, rev. 3 | > > > pcmcia3 at pcic0 controller 1 socket 1 | > > > ep2 at pcmcia3 function 0 "3Com, 3C574-TX Fast EtherLink PC Card, A" | > > > port 0x300/32, irq 9: address 00:60:08:93:80:48 | > > > tqphy1 at ep2 phy 0: 78Q2120 10/100 PHY, rev. 3 | > > > pcic0: irq 5, polling enabled | > > > softraid0 at root | > > > scsibus0 at softraid0: 256 targets | > > > root on rd0a swap on rd0b dump on rd0b | > > > erase ^?, werase ^W, kill ^U, intr ^C, status ^T | > > > | > > > Welcome to the OpenBSD/i386 6.0 installation program. | > > > (I)nstall, (U)pgrade, (A)utoinstall or (S)hell? | > > > ==== | > > > | > > > Seems fairly normal. Did I miss something about 6.1 dropping 486 | > > > support? [/me checks i386.html... still says 486 or better!] | > > > | > > > Turns out that GENERIC can give us a little more useful information | > > > than RAMDISK_CD, as it drops into ddb: | > > > | > > > | > > > ==== | > > > boot> hd0a:/bsd.61 | > > > cannot open hd0a:/etc/random.seed: No such file or directory | > > > booting hd0a:/bsd.61: 7678420+2057220+174556+0+1097728 | > > > [72+501520+501951]=0xb761b4 | > > > entry point at 0x2000d4 | > > > | > > > [ using 1003956 bytes of bsd ELF symbol table ] | > > > Copyright (c) 1982, 1986, 1989, 1991, 1993 | > > > The Regents of the University of California. All rights | > reserved. | > > > Copyright (c) 1995-2017 OpenBSD. All rights reserved. | > https://www.OpenBSD.org | > > > | > > > OpenBSD 6.1 (GENERIC) #291: Sat Apr 1 13:49:08 MDT 2017 | > > > dera...@i386.openbsd.org:/usr/src/sys/arch/i386/compile/GENERIC | > > > kernel: privileged instruction fault trap, code=0 | > > > Stopped at cpuid+0x12: cpuid | > > > ddb> trace | > > > cpuid(80000000,d0d78ef0,d0d78ed8,0,7d) at cpuid+0x12 | > > > identifycpu(d0c7d8a0,d09fbb83,10,0,ffffffff) at identifycpu+0x80d | > > > cpu_startup(d09cefed,d09d1680,16c,8,0) at cpu_startup+0xb9 | > > > main(d02004c6,d02004ce,0,0,0) at main+0x6a | > > > ddb> ps | > > > PID TID PPID UID S FLAGS WAIT COMMAND | > > > ddb> | > > > ==== | > > > | > > > Looks like it's trying to run the CPUID instruction, which this | > > > processor probably doesn't support. Maybe this was an accidental | > > > breakage, rather than intentionally dropping 486es? Time to examine | > > > the CVS logs, I guess. (A -current snapshot also fails in the same | > > > manner, so something happened between 6.0 & 6.1.) | > > > | > > | > > Looks like I broke this about a year ago: | > > | > > 1.592 (mlarkin 14-Oct-16): | > > 1.592 (mlarkin 14-Oct-16): cpuid(0x80000000, regs); | > > 1.592 (mlarkin 14-Oct-16): if (regs[0] >= | > 0x80000006) | > > 1.592 (mlarkin 14-Oct-16): | > cpuid(0x80000006, ci->ci_extcacheinfo); | > > | > > I did test this on 486, but apparently qemu's emulated 486 isn't really a | > > proper 486. I'll see what I can do to solve it for you. | > > | > > Thanks for reporting it. | > > | > > -ml | > > | > | > I think I have a fix for this but I just want to set expectations | > properly. I don't think it's going to work even with the fix as I don't | > believe | > we can boot in 16MB anymore. | > | > -ml | > | > | | | -- | May the most significant bit of your life be positive. -- >++++++++[<++++++++++>-]<+++++++.>+++[<------>-]<.>+++[<+ +++++++++++>-]<.>++[<------------>-]<+.--------------.[-] http://www.weirdnet.nl/