Details on problems booting with EDEN Samuel 2 processor

[Stephen Borrill <netbsd%precedence.co.uk@localhost>]

I noticed after upgrading from NetBSD 3 to 4 on my Eden Samuel 2 box, that 
I could no longer boot a gzipped kernel. The bootloader would hang during 
the first stage of loading the kernel (i.e. display something like:

booting hd0a:netbsd- starting in 0
88131||-

Ctrl-Alt-Del works at this point.

Note that counter has counted up but cursor positioning has gone a bit 
odd. I've also seen on occasion that holding a key down during the kernel 
load messes up the spinner and can even make the kernel attempt boot up in 
a different graphics mode. Very strange...

So, armed with a pencil, paper and patience, I worked through combinations 
of mbr, bootxx_ffsv1, /boot, kernel versions and gzipping.

Observations:

- version of mbr code made no difference.

- bootxx_ffsv1 from NetBSD 4 (and current) resets the machine completely. 
I've committed a fix to this (build it with -DEPIA_HACK) and submitted a 
pullup request for NetBSD 4.

- once I'd built bootxx_ffsv1 with EPIA_HACK, there was little difference 
between v3 and v4 versions. However, it seems that v4 is more 
unreliable; in about 30% of boots it hangs. It doesn't seem to be 
related to cold vs warm reset.

- /boot from NetBSD 3 will fail to boot the kernel if there has been any 
key press. i.e. it will load a kernel if left alone, but if a key is 
pressed and then "boot" is entered at the boot prompt, it will fail even 
though it's the same kernel

- /boot from NetBSD 3 will happily boot either gzipped or non-gzipped 
kernels

- /boot from NetBSD 4 does not have the key press problem

- /boot from NetBSD will always fail loading a gzipped kernel, but will 
reliably load a non-gzipped kernel (subject to the bootxx_ffsv1 
unreliability above).

I'm attempting to migrate our (meaning my company's) installed base from 
NetBSD-3 based version to NetBSD-4. At the moment, the only work around 
seems to be to keep an old copy of /boot around (which I don't want - I 
should be able to build from a netbsd-4 tree).

All suggestions welcome!

--
Stephen