Hi *,
Just a stupid question here for those of you that have Mac hardware. Of all
the Mac hardware in existance right now, all Macs have at most one PCI bus
right?
Thanks for any info!
Regards,
Tom
--
Tom Gall - PowerPC Linux Team "Where's the ka-boom? There was
Linux Technology Center supposed to be an earth
(w) tom_gall@vnet.ibm.com shattering ka-boom!"
(w) 507-253-4558 -- Marvin Martian
(h) tgall@uswest.net
http://oss.software.ibm.com/developerworks/opensource/linux
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From: Ani Joshi <hidden> Date: 2000-08-15 19:14:09
Most Macs have 1 bus (almost all from the OldWorld series), but some 9x00
have 2 busses. Also recent Apple G4's have 3.
ani
On Tue, 15 Aug 2000 tom_gall@vnet.ibm.com wrote:
Hi *,
Just a stupid question here for those of you that have Mac hardware. Of all
the Mac hardware in existance right now, all Macs have at most one PCI bus
right?
Thanks for any info!
Regards,
Tom
--
Tom Gall - PowerPC Linux Team "Where's the ka-boom? There was
Linux Technology Center supposed to be an earth
(w) tom_gall@vnet.ibm.com shattering ka-boom!"
(w) 507-253-4558 -- Marvin Martian
(h) tgall@uswest.net
http://oss.software.ibm.com/developerworks/opensource/linux
From: Michel Lanners <hidden> Date: 2000-08-15 19:39:21
Hi Tom,
On 15 Aug, this message from tom_gall@vnet.ibm.com echoed through cyberspace:
Just a stupid question here for those of you that have Mac hardware. Of all
the Mac hardware in existance right now, all Macs have at most one PCI bus
right?
Wrong :-)
As has been said before, the 9x00 have two PCI busses on two identical
bandit host bridges.
Also, the 73/75/76/85/8600 have an additional bus called VCI by Apple,
for accessing video in/out hardware, that behaves exactly like a PCI
bus.
Then, there are newer Macs, with those based on UniNorth having three
PCI buses (AGP counted in).
Michel
-------------------------------------------------------------------------
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Hi Tom,
On 15 Aug, this message from tom_gall@vnet.ibm.com echoed through cyberspace:
quoted
Just a stupid question here for those of you that have Mac hardware. Of all
the Mac hardware in existance right now, all Macs have at most one PCI bus
right?
Hi All,
I thank you much for the information. It took me a little bit but as I've been
looking at the PCI code I ran across the pmac PCI implementation which
definately has support for more than one PCI bus.
Where I'm coming from is getting the same thing working on IBM PowerPC
hardware for multiple pythons... fun fun fun...
Thanks again!
Wrong :-)
As has been said before, the 9x00 have two PCI busses on two identical
bandit host bridges.
Also, the 73/75/76/85/8600 have an additional bus called VCI by Apple,
for accessing video in/out hardware, that behaves exactly like a PCI
bus.
Then, there are newer Macs, with those based on UniNorth having three
PCI buses (AGP counted in).
It's definately interesting to hear that AGP is really just another PCI... or at
least treated that way. Being PCI/AGP stupid I appreciate the info... if it's
just another "PCI" of sorts, doesn't that have performance implications or is
that addressed really by the hardware implementation as apposed to the Linux
side of things?
Regards,
--
Tom Gall - PowerPC Linux Team "Where's the ka-boom? There was
Linux Technology Center supposed to be an earth
(w) tom_gall@vnet.ibm.com shattering ka-boom!"
(w) 507-253-4558 -- Marvin Martian
(h) tgall@uswest.net
http://oss.software.ibm.com/developerworks/opensource/linux
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From: David Riley <hidden> Date: 2000-08-16 00:19:25
tom_gall@vnet.ibm.com wrote:
It's definately interesting to hear that AGP is really just another PCI... or at
least treated that way. Being PCI/AGP stupid I appreciate the info... if it's
just another "PCI" of sorts, doesn't that have performance implications or is
that addressed really by the hardware implementation as apposed to the Linux
side of things?
It really is just another PCI (there is a 66 MHz PCI specification, and AGP uses
it), though there are improvements made (for example, sidebanding, which gives us
the 2x and 4x modes). Additionally, it's adapted on the Intel side of things for
"write combining" (if anyone comes up with an exact definition of how that works,
please let me know). I'm not sure what you mean by performance implications, but
PCI isn't a horrible bus to start with...
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It's definately interesting to hear that AGP is really just another PCI... or at
least treated that way. Being PCI/AGP stupid I appreciate the info... if it's
just another "PCI" of sorts, doesn't that have performance implications or is
that addressed really by the hardware implementation as apposed to the Linux
side of things?
It really is just another PCI (there is a 66 MHz PCI specification, and AGP uses
it), though there are improvements made (for example, sidebanding, which gives us
the 2x and 4x modes). Additionally, it's adapted on the Intel side of things for
"write combining" (if anyone comes up with an exact definition of how that works,
please let me know). I'm not sure what you mean by performance implications, but
PCI isn't a horrible bus to start with...
`write combining' means that the PCI bridge will buffer successive writes to
successive addresses and combine them into one burst of writes. Since burst
writes are more efficient than individual writes (which require an address
setup operation for every write), this is a win. Of course you cannot always
use write combining (think about register writes), but for frame buffer
accesses it's nice.
BTW, if you look at the specs for the host bridge IBM used in the (dead?) POP
design, you'll see that it actually has 2 PCI buses: one at 33 MHz and one at
66 MHz. The 66 MHz can be used as an AGP bus as well, as is done in the POP
design.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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