Newer OpenBSD (7.5, 7.4, ...) can not install on PC Engines apu2c4 (with OpenBSD 6.3)

[joly_new]

Dear community,

I've lit up an old PC Engines apu2c4 (amd64) where I tested OpenBSD a few years on. It runs perfectly, but with OpenBSD 6.3, I wanted to upgrade it (especially hearing about sysupgrade since version ... 6.7 ?). It has no wifi adapter, I could bring internet to it via tethering with my phone in usb, succeeded to update its resolvconf so that it ended connected, then I realize I would have too much work for upgrading version by version (and did not find the archive ... should search).

As it is a test router, I can simply re-install last OpenBSD. I downloaded install75.img (for amd64), dd it into an sub drive, plugged an usb-DB9 cable to my computer, and ... I could force the usb drive to boot (SeaBIOS choice), and i have 2 lines :

cannot open hd0a:/etc/random.seed: no such file or directory

which seems normal, il is created after this step, and

booting hd0a:/7.5/amd64/bsd.rd : [some numbers+numbers]=0xaa40e8
entry point at 0xffffff0100100

and then SeaBIOS reboots ... an the same repeats indefinitely.
I've check the checksum of the download, tested with another usb drive, tested with install7.4.img, tried with install75.iso (one never knows) ... and all the writings of the images via dd and retested via Balena Etcher : always the same result !

I have seen an hint in my search on the forum : where should I search at first ?

[J65nko]

Have you seen this? : PC-Engines apu2c4 install reboot loop But this is with OpenBSD 6.0 ....
In case this does not solve your problem, you can search the misc mailing list archives at that marc.info site for 'apu2c4'.

[joly_new]

No, I haven't (I didn't know the MARC archive btw, thx). It relates to the same error messages, and used a long / indirect technique, but it worked for him, great. It made me realize he used installxx.fs installation file, thx ... so I looked around, at the example website I used in 2020 with OpenBSD 6.4, and other tutorials on other sites/github pages : everyone was also using whether the installxx.fs or the minirootxx.fs installation file.
Pb: the install75.fs file is not provided anymore : can I find it with a dedicated procedure / hook ?