Hi,
I am about to follow this guide to install FreeBSD with ZFS root inside a MBR slice. But after reading the instructions I started to wonder on how step 10 works:
[CMD=""]dd if=/mnt2/boot/zfsboot of=/dev/ad0s3 count=1[/CMD]
Writes the first the first 512 Bytes of zfsboot to the start of the slice. Ok. But now:
[CMD=""]dd if=/mnt2/boot/zfsboot of=/dev/ad0s3a skip=1 seek=1024[/CMD]
Writes the rest of zfsboot inside the slice, but starting to write at a offset of 512kB.
The Section 1.4: Boot Block of the ZFS specification says that 3.5MB of reserved space are at this position. This explains why the 64k of zfsboot fit in there without bothering the filesystem.
I guess the first block will load the rest of the code from that position when it is executed during the boot process. But I don't like to blindly follow the linked wiki article.
So here is my question: Is there any documentation for /boot/zfsboot? I mean without the wiki article I would have no idea on how to use it. There seems to be no no man page mentioning it. And searching the net was also without luck.
I am about to follow this guide to install FreeBSD with ZFS root inside a MBR slice. But after reading the instructions I started to wonder on how step 10 works:
[CMD=""]dd if=/mnt2/boot/zfsboot of=/dev/ad0s3 count=1[/CMD]
Writes the first the first 512 Bytes of zfsboot to the start of the slice. Ok. But now:
[CMD=""]dd if=/mnt2/boot/zfsboot of=/dev/ad0s3a skip=1 seek=1024[/CMD]
Writes the rest of zfsboot inside the slice, but starting to write at a offset of 512kB.
The Section 1.4: Boot Block of the ZFS specification says that 3.5MB of reserved space are at this position. This explains why the 64k of zfsboot fit in there without bothering the filesystem.
I guess the first block will load the rest of the code from that position when it is executed during the boot process. But I don't like to blindly follow the linked wiki article.
So here is my question: Is there any documentation for /boot/zfsboot? I mean without the wiki article I would have no idea on how to use it. There seems to be no no man page mentioning it. And searching the net was also without luck.