Hello Greg. Thank you for the extensive answer. ## Sectors 0 and 1
Would sector 0 simply correspond to what is called the Partition Boot Record? * There are bits of disklabel onto sector 1 indeed. ## Sectors 2-13 and getting closer The bootxx_ffsv2 and bootxx_ext2fs are both 6656 bytes (13 sectors) so one could assume the home for boot blocks is rather the same. As an attempt to figure that out, I eventually filled-up an ext2 file-system with with random bytes and checked what space at the beginning happens to stay intact. Not much happens until sector 434 and 436. So I guess there's lots of room there for whatever purposes. I found out why I had no magic. It was because fsck.ext2 cleans-up sector 2 and above. Its output is pretty self-explanatory as it also talks about "Bad magic". # fsck.ext2 -y /dev/sda1 e2fsck 1.44.1 (24-Mar-2018) ext2fs_open2: Bad magic number in super-block fsck.ext2: Superblock invalid, trying backup blocks... /dev/sda1 was not cleanly unmounted, check forced. Pass 1: Checking inodes, blocks, and sizes So I finally tried the dirty way of `dd`ing bootxx_ext2fs right onto the partition but now without fscking. The result is NetBSD/x86 ext2fs Primary Bootstrap Boot failed (errno 2): Can't open /boot Reboot and Select proper Boot device or Insert Boot Media in selected Boot device and press a key It suggests the phase 1 boot strap code needs have a clue on its own device name. Maybe it simply needs a disklabel. I am stuck again, although I could try to dd/push a working disklabel over there. I though I could avoid that, as the netbsd kernel seems to generate a soft-generated `e` partition. ## 63 vs 64 vs 2048 On NetBSD x86 we're still starting at 63. In my previous attempt, I used the gnu/linux fdisk and cfdisk utilities with their modern defaults so the partition was starting at sector 2048. While using `fdisk -c=dos` I could create a partition starting at 63 (the default was indeed 64). I do not think this makes a big difference for my purpose of boot strapping netbsd. ## /boot supports ext2fs? > I am unclear on which filesystems /boot can handle, other than > ffs1/ffs2. Surely that includes ext2fs and fat32, or we'd have > /boot-foo for them and I'd have heard about it. I would not be so certain. As far as I've seen, bootxx_ext2fs is a pretty new thing and nothing tells the netbsd phase 2 boot strap can use it. I do not know where to check tho. ## good news > In a filesystem/partition, sectors 2-15 contain bootxx_foo. These read > the fs and find /boot. On some systems (sparc?) they are patched with > the sectors of /boot, but on x86 they read the fs and this isn't > necessary. /boot always reads the fs to find /netbsd. This means on amd64 my problem and task is not about hard-coding the location of /boot. ## hardware I should have mentioned bare-metal IaaS or root-server only, not VPS. This is a Supermicro SYS-5038MA-H24TRFG-ON002 and I reach its physical console through IPMI & Java. NetBSD current dmesg here: http://tmp.nethence.com/dmesg/xc2015.txt (that dedibox dates 2015) The _rescue_ environment I am trying to install NetBSD from -- is an Ubuntu Bionic. I got all the tools I want including qemu-kvm which allowed me to install NetBSD as such. But I am trying to find the best approach. FreeBSD 11.1 is also available. I have no issue with the MBR. I have only issues with bootxx_ext2fs versus an mkfs.ext2. * sys/arch/i386/stand/bootxx/pbr.S sys/arch/i386/stand/bootxx/bootxx.S https://wiki.netbsd.org/how_netbsd_boots_on_x86/ -- Pierre-Philipp Braun SNE Russia https://os3.su/
