[rescue] Sparc OS Install over serial

Jonathan C. Patschke jp at celestrion.net
Wed Jan 7 17:19:43 CST 2004

On Wed, 7 Jan 2004, Patrick Finnegan wrote:

> Hell, it shouldn't even be that hard.  All you *really* need to do is
> make something that'll load a memory image over the serial port, and
> use any generic Sparc Linux netboot image... they're a kernel plus a
> ramdisk image.  Just load that into memory.  In fact, if you're clever
> enough, you could put enough stuff into the ramdisk image to start up a
> SLIP or PPP connection over the serial port, and install over that.

I think you folks are making this harder than it needs to be.  The
OpenBoot forth monitor includes commands for poking words into memory.
All you really need is a VTserver-like tool that reads a bootable memory
image (say, a kernel with a ramdisk image tacked behind it, like is the
case with the OpenBSD miniroot kernel), converts it into OBP commands to
poke that data into memory, and have it finally send a jump to have the
sparc start executing code.

Then, start running the code already in memory.  Voila, OS loaded over

The necessary OBP frobbage (poking words into memory and telling the
resulting OS how much memory to reserve for its image) is documented in
the "Writing FCode Programs" manual from Sun:


More is documented (specifically, how to enter a SPARC assembly-language
routing to perform the jump) in the "OpenBoot 3.x Command Reference


At this, point $boss should realize that it's entirely possible, and
you're spared the actual problem of writing any code.

If you're interested in doing this, you could rip out the pdp11-specific
bits of vtserver and replace them with OBP-specific bits.  This would be
a win, since the terminal passthrough bits are already working so that
you can use the bootsystem as a console.

Jonathan Patschke  ) "Some people grow out of the petty theft of
Elgin, TX         (   childhood.  Others grow up to be CEOs and
USA                )  politicians."                    --Phorist

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