i386/amd64 image generated trough mkimage stuck on primary bootsrap at boot

[br0nko <br0nko%protonmail.com@localhost>]

Hi,

I wanted to resurrect an old i386 alix box, and I did follow the guide to create a custom image trough mkimage (https://www.netbsd.org/docs/guide/en/chap-inst-media.html#chap-inst-media-creating-live-images). I did first try on amd64 so that I can first test on my laptop. Build was successful but when I boot the USB key, I'm stuck on primary bootstrap ("NetBSD/x86 ffsv1 Primary Bootstrap"), no error. However I can boot it from grub (installed on the laptop hard-drive) , image is fully functional that way.

Here's what fdisk show:

=========================================================
bash-5.1# vndconfig vnd0 /home/phil/alix-netbsd.9.2.img
bash-5.1# fdisk -vv /dev/rvnd0
Disk: /dev/rvnd0
NetBSD disklabel disk geometry:
cylinders: 765, heads: 64, sectors/track: 32 (2048 sectors/cylinder)
total sectors: 1568447, bytes/sector: 512

BIOS disk geometry:
cylinders: 98, heads: 255, sectors/track: 63 (16065 sectors/cylinder)
total sectors: 1568447

Partitions aligned to 16065 sector boundaries, offset 63

Partition table:
0: NetBSD (sysid 169)
    start 63, size 1568384 (766 MB, Cyls 0/1/1-97/160/62), Active
        beg: cylinder    0, head   1, sector  1
        end: cylinder   97, head 160, sector 62
        Information from PBR:
            Not bootable: All bytes are identical (0x00)
            Not bootable: Bad magic number (0x0000)
1: <UNUSED> (sysid 0)
    start 0, size 0
        beg: cylinder    0, head   0, sector  0
        end: cylinder    0, head   0, sector  0
2: <UNUSED> (sysid 0)
    start 0, size 0
        beg: cylinder    0, head   0, sector  0
        end: cylinder    0, head   0, sector  0
3: <UNUSED> (sysid 0)
    start 0, size 0
        beg: cylinder    0, head   0, sector  0
        end: cylinder    0, head   0, sector  0
First active partition: 0
Drive serial number: 0 (0x00000000)
=========================================================

I did try to reinstall the primary bootstrap:

installboot -v -o timeout=5 /dev/rsd0a /usr/mdec/bootxx_ffsv1

But it didn't fix the problem either.
I'm running out of ideas, I don't really see what I'm missing. Any help would be highly appreciated.

Br0nko