On 2025-08-04 19:26, Perry Metzger wrote:
On 8/4/25 12:36, Jason Thorpe wrote:
On Aug 4, 2025, at 7:45 AM, Johnny Billquist<bqt%softjar.se@localhost>wrote:
I'll just top-post to be lazy.
First of all, as you know, MOP is the "native" way to netboot DEC
machines from back in the day. And MOP sortof fills the place of
both DHCP and TFTP in one. But it's more targeted for the explicit
need of netbooting and remote management. But in a sense, for VAXen,
it would be great if we had the possibility of getting all the
netbooting though MOP and not need DHCP and TFTP. Not sure if that
is possible, though.
Can MOP supply the IP address to the system? If not, you're not
goingto be eliminating DHCP (or BOOTP).
Certainly, but it's nice not to have to load boot blocks that then
just load the kernel if you can just load the kernel in one step. The
OS will use dhclient to get its address.
I'm starting to suspect you don't understand the full process of the
booting.
The boot block is a really simple piece of code that resides in the
first block(s) of a disk, and the sole purpose of that code is to read
in the /boot image.
The /boot image in turn is responsible for reading in the kernel.
The boot block never reads in the kernel. It's not advanced enough to be
able to deal with that. And it can't be. There are limits on how much
code you can stash into the boot block.
If you substitute "/boot" for whenever you say "boot block", then you
are more in the right place. And MOP reads in /boot. And the next step
from there is reading in the kernel. But at the moment, dhcp is needed
here, because boot needs to know which address to fetch the kernel from,
as well as what filename to fetch, and some other bits. And then, once
the kernel have booted, it will also request what IP address itself
should use.
What would be nice would be if /boot, instead of depending on dhcp and
tftp, could use MOP as well, to get the kernel, as well as the
parameters for getting the kernel and its own configuration parameters.
Then you could probably skip tftp altogether, and dhcp would be more for
normal operation, and not needed for the initial booting.
Although, since dhcp would probably always be needed/used anyway, there
is probably less arguments for trying to remove that dependency.
Johnny