mfii0 disappears on warm reboot

Hi, all,

I have quite a few older systems that have run NetBSD wonderfully for many 
years. They're AMD Athlon AM1 systems that boot very quickly and take very 
little power.

I'm now installing LSI MegaRAID cards in a few. They run fine, but for 
some reason the RAID cards aren't seen after a warm reboot:

< mfii0 at pci1 dev 0 function 0: "ServeRAID M5016", firmware 23.34.0-0019, 1024MB cache
< mfii0: interrupting at msix1 vec 0
< mfii0: Max 256 VD support
< scsibus0 at mfii0: 64 targets, 8 luns per target
---
> mfii0 at pci1 dev 0 function 0autoconfiguration error: : unable to map registers

See:
https://www.klos.com/~john/dmesg_raid.txt
https://www.klos.com/~john/dmesg_no_raid.txt

This happens both when booting original bootblocks and when booting via 
UEFI, and this happens both with NetBSD 9.3 and with NetBSD 10.0_BETA, 
both from the last few days.

A restart, then entry in to BIOS and a save, or a hardware reset button 
press, lead to a boot with mfii0 working (the boot time MegaRAID messages 
are seen.

A warm reboot restarts without seeing the MegaRAID boot messages and mfii0 
isn't configured.

Is this a known issue? Is there some way to force a full reset of 
the system and/or force a reset of mfii* on reboot?

Thanks,
John