Bootable Network File System in ROM for Amiga

[Mrs Beanbag]

Hi Toni, just been having a discussion over on Amiga.org about making rommable filesystems. Specifically NFS, so an Amiga can net boot without any disks. Do you think this is possible?

[Toni Wilen]

Originally Posted by Mrs Beanbag

Hi Toni, just been having a discussion over on Amiga.org about making rommable filesystems. Specifically NFS, so an Amiga can net boot without any disks. Do you think this is possible?

Any Amiga filesystem (as long as it does not do anything stupid) can be made bootable quite easily, filesystem itself does not need any extra support, all the magic is done by KS strap module and expansion.library. My ACA620 reset proof ram disk for example does it.

But... Directly booting from network filesystem is of course impossible because you need working network first

Note that creating bootable dos node is quite tricky, it needs special handling that isn't documented very well. (For example you need to create some fake autoconfig structures..)

[Mrs Beanbag]

I realise the network drivers/TCP stack must also be resident in ROM as well, could that work? I imagined maybe booting into a "ROM" disk first (essentially a RAM disk image with things preloaded on it), mounting a reset-proof NFS from there and then rebooting. TCP would have to survive reset too but I imagine that's possible? Or maybe the NFS handler could be modified to start TCP on demand.

[Toni Wilen]

Originally Posted by Mrs Beanbag

I realise the network drivers/TCP stack must also be resident in ROM as well, could that work? I imagined maybe booting into a "ROM" disk first (essentially a RAM disk image with things preloaded on it), mounting a reset-proof NFS from there and then rebooting. TCP would have to survive reset too but I imagine that's possible? Or maybe the NFS handler could be modified to start TCP on demand.

I am 100% sure network stack requires dos.library and other things that are only available after boot drive boots.

Booting to "ROM disk" that inits network, changes assigns and continues booting from network drive is the only working solution.

Note that being rommable or not rommable is not a problem, you can always create rommable "loader" module that copies and relocates non-rommable module(s) to RAM.

(and I think these posts should be moved from this thread)

[Mrs Beanbag]

Presumably dos.library is available by the time startup-sequence is loaded? So if the TCP stack were started by the NFS handler on first file access, it could do it. I have FTP on my Amiga that is mounted at boot but doesn't access the network until I try to open it.

[Toni Wilen]

First boot filesystem file access is multiple Lock()s. Before startup-sequence is run.

After boot filesystem has been found, following happens:
- DOS gets initialized (via BootPoint "bootblock")
- DOS creates boot volume assigns. (SYS:. C:, S:, LIBS: etc..)
- S:Startup-sequence is opened
- Boot shell is started.
- Shell starts executing S:Startup-sequence.
- Normal shell screen/window opens when/if shell outputs something.

This means first NFS access is first Lock() (ACTION_LOCATE_OBJECT) which will require working network. Even if NFS fakes/delays it internally, opening of startup-sequence or first command in s-s (ACTION_INPUT/ACTION_READ) really require working network.

-> TCP stack MUST be ROM-built-in and I can guarantee it is not designed for it, at least it will require config files (=dos must be available)

[Mrs Beanbag]

I think we could fake/delay it internally, or make some kind of nfs/RAD disk hybrid, so that it can be initialised with some directories and config files before the network starts. If the TCP stack was coded into the NFS handler it could get the config file out of itself directly without going through DOS.

But you would have to boot to a ROM disk first to do the setting up.