Latest thrift store find - Ruby iMac (400MHz G3)

Cameron Kaiser spectre at
Mon Jun 15 08:15:03 CDT 2009

> > > Leopard (10.5) requires a /G4/ of at least 867MHz. The kernel is
> > > compiled against a G4 and will not boot on a G3. The check can be
> > > bypassed with an app called LeopardAssist or an OpenFirmware hack.
> >
> > Compiling against a G4 implies there is AltiVec (without a non-AltiVec
> > option) code in the kernel. To my knowledge the Leopard kernel does
> > not have such a dependency; where did you see this?
> >
> > Not that I advise bothering with Leopard on a G3, mind you :)
> This has been discussed at very considerable length on the LEM
> UnsupportedOSX list and it appears to be quite definite; for more
> info, I'd suggest asking there.. It does not necessarily imply that
> the kernel uses AltiVec, although I don't find that massively
> implausible; for instance, the Linux kernel uses MMX and SSE to
> accelerate software RAID functions. All it implies, AFAICS, is that as
> it loads the kernel checks that it's on a G4-class or better CPU and
> aborts if it's not.

I think we're talking two different things here. I have it on reasonably
good authority that Leopard will boot on a G3, *if* you install it
on a supported machine and swap drives, *or* you fudge OpenFirmware and
fool the Installer. I read your post to say that even that configuration
won't boot on a G3. Did I misunderstand?

If there is an AltiVec dependency in the kernel, then I would imagine that
the kernel either would crash outright on a G3, or certain things would
break. OTOH, certain things do break under Leopard on a G3, so maybe there's
some AltiVec code there after all, just not in the bootstrap.

------------------------------------ personal: --
  Cameron Kaiser * Floodgap Systems * * ckaiser at
-- Perl scripting: the ultimate open source software. -------------------------

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