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Re: SS20 and SMP using Ross modules

On Wed, Nov 02, 2005 at 10:38:11PM +0000, Mark Morgan Lloyd wrote:
> I have here an SS20 which has run Woody reliably for an extended period. It has
> 2x Ross 625 CPUs, PROM 2.25R and 256Mb RAM.
> It runs single-processor 2.4.27 from Sarge reliably, but attempting to boot SMP
> gives an interrupt 15/watchdog error.
> If it is given this sequence of commands:
> reset
> ross625
> ibuf-off
> 2 switch-cpu
> ibuf-off
> 0 switch-cpu
> boot


> it will boot into SMP, but eventually fails with a "wrong magic" error.

eventually fails in what way?  during boot?  after running for two

> If the Ross modules are replaced by Suns then it will boot either single
> processor or SMP successfully, and run reliably.
> Reverting to Ross modules, if I build a standalone kernel I find it's too large
> to boot from disc, but I can boot it over the LAN (boot net root=/dev/sda2) and
> the system runs SMP reliably. However I notice that while the BogoMIPS rating of
> a single CPU is 150 when running SMP it's dropped to 104 per processor- I
> thought this was calibrated using a tight loop?
> I'm assuming that none of the core developers will be looking at this because of
> the age of the hardware, and I don't have the hardware information to even start
> making sense of this sort of problem. However as a workaround can anybody point
> me at the documentation that describes the Debian/SPARC-specific kernel rebuild
> procedure- running the standard "make vmlinux" gives me a kernel image of around
> 2Mb.
> My position is that I'm keen on promoting Sun kit for in-house use, but having
> to boot over the LAN makes it difficult to argue that they are a viable
> alternative to PCs, and if I'm not confident making that argument I'm not going
> to put my neck on the block and ask for money for newer systems.

Well, try configuring a smaller kernel, with more things defined as
modules.  Failing that, try using an initrd image for boot time module

These troubles don't really translate to being apropos to the question,
however, as experience with this ancient hardware isn't typical of
experience with US2 or US3, or, dare I say it, US4 processors.  I don't
know if anyone has even tried to fire up Linux on a US4 box.

My opinion, while possibly inaccurate, is that US2 based machines are
the best supported by Linux these days.



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