harddrive no memory ---FreeBSD scenario

[Oliver Fromme]

Julian Elischer wrote:
 > Markus Boelter wrote:
 > > 
 > > > Apart from wondering how you're getting the motherboard to get past
 > > > POST without RAM, I'm wondering how you'd get the bootloader and
 > > > 
 > > [...]
 > > 
 > > The guys at Linux/OpenBIOS did some Cache-as-RAM stuff. Maybe you can 
 > > also put (burn) the kernel directly into the BIOS chip and bott with 
 > > that kernel. This is just an idea out of my head - nothing tested and no 
 > > research done in this field. :-)
 > 
 > A modern CPU with 4Mb of cache and no ram has more ram than my first system.
 > If you wanted to you might be able to get FreeBSD 1.1 up in such an
 > environment.

I had FreeBSD 2.2-stable installed on an old notebook with
4 MB RAM (actually less, because ~ 0.5 MB was lost VGA
mappings and registers etc.).  It was very usable for
simple things like text editing and as a terminal.

 > (Just no DMA capability, so no floppies).

You can access the FDC in PIO mode, no DMA necessary.  It
won't be very efficient, but a floppy drive is slow anyway.

You'll have to access the hard disk in PIO mode, too, so
that will also be slow.  You'll probably want to avoid
swapping / paging at all.  That means that your whole
working set has to fit in 4 MB (minus what the kernel
needs).  That'll probably be difficult, depending on
what you're planning to use the machine for.

Bottom line:  I think it's useless.  :-)

It makes more sense to eliminate the hard disk instead
of the RAM.  And running diskless is perfectly possible
(and quite easy) with FreeBSD; I've done such setups in
the past.

Best regards
   Oliver

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