Messages in this thread |  | | | Date | Wed, 8 Sep 2004 02:55:15 -0400 | | From | Jon Smirl <> | | Subject | Re: multi-domain PCI and sysfs |
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Another part I don't understand... PCI VGA hardware is designed to respond to IN/OUT instructions to port space. ppc64/ia64 don't have IN/OUT port instructions. Is there some special hardware on ppc64/ia64 that declares part of the PCI IO space "legacy space" and turns read/writes there into IN/OUT port cycles on the PCI bus so that the legacy hardware can see the accesses?
On machines without this "legacy space" translation hardware (ie all 32b x86 bit machines) I can only have a single VGA adapter active since there is only a single legacy space and inb/outb are real instructions.
On machines with "legacy space" translation I can have one active VGA card per translator. How do I know how many translators there are? Is only one per domain/segment allowed?
How does ppc32 handle VGA port instructions, is the "legacy translation" space at the bottom of the PCI address space?
I looked at io.h on IA64, how do apps select which legacy IO space they are using? Now I see add_io_space() and related code.
Maybe it's not a good idea to have a 32b x86 person writing this driver. Is there a cross platform structure that corresponds to IO spaces?
-- Jon Smirl jonsmirl@gmail.com - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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