Re: Linux not adhering to BIOS Drive boot order?

[David Weinehall]

On Thu, Jan 18, 2001 at 10:53:16PM +0200, Matti Aarnio wrote:
> On Thu, Jan 18, 2001 at 09:59:06AM -0800, [e-mail] wrote:
> ...
> > > Yes.  PCI-based drivers will most likely use bus order since the kernel
> > > provides facilities to do this easily.  For a single driver driving
> > > multiple cards on multiple bus types, who knows.
> > 
> > Multiple bus types... Compaq server with PCI and EISA, for example? IIRC
> > the EISA bus is bridged onto one of the PCI busses. Perhaps a
> > breadth-first scan; PCI busses first, then bridged devices on PCI, then
> > internal non-PCI busses, then external busses.
> > 
> > Are there any systems where a non-PCI bus is not connected through a
> > PCI-foo bridge?
> 
> 	Yes.
> 
> 	Oh, you propably won't meet them in PC world, but pick
> 	any UltraSPARC; PCI and SBUS are on parallel "hoses".
> 	("hose" is term used at Alpha code for the IO-bus to
> 	 CPU/MEMORY bus interface, sort of "north bridge".)
> 	Actually those UltraSPARC systems have core-bus called UPA,
> 	and IO-busses, like PCI and SBUS, are connected there...
> 
> 	Also these "big" systems often do come with multiple "hoses"
> 	of same type.
> 
> 	If you look carefully at intel things, there is this "FSB"
> 	which is the real core-bus, and IO-busses hang on it.
> 
> 
> 	I have never myself seen big Digital Alpha system where IO-
> 	busses are anything but PCI, but there exists options to place
> 	there FutureBus+, PCI, VME, TurboChannel, and several other
> 	DEC proprietary things.  With 43-45 bits of physical address
> 	space out of the processors, it is trivial to plug in multiple
> 	32-bit address space busses.
> 
> 	In coherent view NUMA implementation of Linux, there possibly
> 	comes even the detail about which NUMA node the busses reside at.

I'm pretty sure the IBM PC-Server 700 (8 MCA-slots and 8 PCI-slots
and a lot of other cool stuff) doesn't have the MCA-bus bridged
onto the PCI-bus. Maybe the other way around. I'd be happy to get one
of these machines to test this, but they seem to be a little hard
to get by for free... :^)

/David
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