Re: ofwboot versions and upgrading

[Greg Troxel <gdt%ir.bbn.com@localhost>]

matthew green <mrg%eterna.com.au@localhost> writes:

>    ofwboot    kernel  status
>    3  3       works (my machine to be upgraded is fine)
>    4       4       works (another of my machines)
>    3       4       fails, kernel complains about bootinfo
>    4       3       ???
>    
>    What I would like to know is:
>    
>      If I put the netbsd-4 ofwboot in place on my netbsd-3 system, can I
>      still boot the netbsd-3 kernel (netbsd.ok) if I need to?
>
> this should work.  you can put ofwboot in as a different name as
> boot that instead of the default.  something like this:
>
> ok> boot ofwboot.new netbsd.new
>
> works iirc.

I put the old (netbsd-3) ofwboot as ofwboot.ok to go with netbsd.ok, and
the netbsd-4 versions as ofwboot and netbsd.

> if new ofwboot can't boot old netbsd, that seems like a bug to
> fix.

Indeed, but this machine is remote so I wanted to avoid losing.

>    I have installed bootblk from the head of the netbsd-3 branch.  Can
>    this load the netbsd-4 ofwboot?  Answer: the files /usr/mdec/bootblk
>    are byte-for-byte identical on netbsd-3 and netbsd-4, so sure.
>
> "bootblk" and "ofwboot" are separate.  the former is a forth
> bytecode program to load the latter, which is a normal ELF
> file (32 or 64 bit.)

I dimly remember on i386 that there was a new 1st/2nd stage bootblocks
and a new /boot and that the older bootblocks (the analog of bootblk, I
think) couldn't boot the newer /boot, so if you updated in the wrong
order the system was hosed.  So I was worried about updating ofwboot
with older 1st-stage bootblocks.  But besides knowing that 'bootblk' has
not changed, it sounds like you're saying that the interface to /ofwboot
has not changed.

It would be nice to backport the ofwboot changes to netbsd-3 so that
being up-to-date on netbsd-3 was sufficient to boot netbsd-4 kernels.
But I realize that's both work and risk of instability on netbsd-3, and
that the standard update method is to boot a cd that updates the boot
blocks.

Thanks for taking the time to answer my questions.