Subject: Re: NetBSD/powerpc on PowerMac (Re: NetBSD server)
To: None <firstname.lastname@example.org>
From: Jason Thorpe <email@example.com>
Date: 01/27/1997 18:41:04
On Tue, 28 Jan 1997 09:07:48 +0900
Masami and Ken Nakata <firstname.lastname@example.org> wrote:
> Last time this line of topic was brought on the port-mac68k list, I
> kind of got the impression from Joson (Thorpe)'s post that
> NetBSD/powerpc ran on PowerPC systems with OpenFirmware support which
> PCI-PowerMacs do have thus it was possible to run NetBSD/powerpc on a
> PCI-PowerMac (not on the NuBus-PowerMacs that are supported by
> MkLinux). I deduced, because device drivers would have to interpret
> OFW ROM each time it does I/O, it would run with some (probably
> significant) performance penalty.
> Would anyone care to clarify?
Well, I'm told that it doens't _quite_ run on PCI Powermacs just
yet (some minor tweaking to resolve some bootstrap issues, I guess),
In any case, you're correct in assuming that using OFW for i/o pays
a performance penalty.
However, the implementation of native drivers should be a mostly
SMOP, given appropriate documentation (or sample code). In order to
support PCI and ISA on systems like Firepowers and Powermacs, only
a small bit of glue code is needed[*]. The rest of the PCI code comes
for free, since it's machine-independent.
[*] This is not strictly true, just yet. NetBSD/powerpc, since it's
still fairly young, lacks the autoconfiguration infrastructure needed
to deal with differing PCI -> Host chipsets. I'm currently working
on code to deal with the PCI -> Host chipsets on the Firepower computers,
and my design (which borrows heavily from NetBSD/alpha's autoconfiguration
model) will allow other PCI -> Host chipsets to be added very easily.
I'm still working out some of the details, and I hope to have something
interesting to post about here, sometime soon.
(FYI, the design I'm working on would also allow non-OFW systems to
be supported by a single kernel.)
Jason R. Thorpe email@example.com
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