In a fit of nostalgia I decided to boot SunOS 4.1.4 up under emulation using qemu-system-sparc. It all seems to work, but I'm trying to remove an annoying manual step.

I'm starting qemu-system-sparc like this:


exec qemu-system-sparc \
    -rtc base=2009-12-13 \
    -drive file=sunos-root.img,format=raw,bus=0,unit=3 \
    -drive file=sunos-home.img,format=raw,bus=0,unit=1 \
    -nographic \
    -bios ss5.bin \

This boots the root disk at SCSI target 3, which matches the Open Firmware devalias for disk:

ok devalias disk
disk           /iommu/sbus/espdma@5,8400000/esp@5,8800000/sd@3,0

Unfortunately, when booting with an Open Firmware ROM (like this one), something insists on setting the diag-switch? setting to true when the system boots:

Incorrect configuration checksum;
Setting NVRAM parameters to default values.
Setting diag-switch? NVRAM parameter to true

That means the system tries (and fails) to boot from the network, dropping to the ok prompt, which requires me to type boot disk to actually boot the system.

If I drop the SparcStation 5 ROM (i.e. get rid of the -bios ss5.bin option), the system boots using OpenBIOS instead, which has a different problem: apparently the disk alias in OpenBIOS doesn't point at target 3:

0 > boot disk Not a bootable ELF image
Not a bootable a.out image
No valid state has been set by load or init-program
0 > boot disk1 Not a bootable ELF image
Loading a.out image...
Loaded 7680 bytes
entry point is 0x4000

Unexpectedly, the magic name is disk1.

So, I have a questions:

  • Is there any way to resolve the Incorrect configuration checksum message that shows up when using Open Firmware? I suspect that would allow the system to boot correctly.
  • Aternatively, is there any way to get OpenBIOS to boot from disk1 by default? You'd think that adding -prom-env boot-device=disk1 would do it, but that doesn't work.
  • 1
    It is an excellent question that makes sense to someone like me who knows nothing about the subject matter. Nicely done. Nov 18, 2020 at 18:05

1 Answer 1


I know of a few people doing this, or at least things much like it. I have found a few links, in case they help.

Any of these any help at all?

If not, I would suggest asking on the SunRescue or ClassicCmp.org mailing lists.

  • How about the source code to SunOS 4.1.4? You can search the IA for it. Jun 4, 2023 at 10:06

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