Messages in this thread Patch in this message |  | | Date | Thu, 9 Nov 2000 17:39:20 +0300 | From | Ivan Kokshaysky <> | Subject | Re: PCI-PCI bridges mess in 2.4.x |
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On Wed, Nov 08, 2000 at 03:48:11PM -0800, Richard Henderson wrote: > Whee! We're back in Bootsville.
Cool! Meanwhile this base/limit stuff got confirmation :-) Here is a patch against bridges-2.4.0t11-rth.
Ivan.
--- 2.4.0t11p1/drivers/pci/setup-bus.c Wed Nov 8 19:44:42 2000 +++ linux/drivers/pci/setup-bus.c Thu Nov 9 15:11:01 2000 @@ -88,14 +88,14 @@ pbus_assign_resources_sorted(struct pci_ ranges->io_end += io_reserved; ranges->mem_end += mem_reserved; - /* ??? How to turn off a bus from responding to, say, I/O at - all if there are no I/O ports behind the bus? Turning off - PCI_COMMAND_IO doesn't seem to do the job. So we must - allow for at least one unit. */ - if (ranges->io_end == ranges->io_start) - ranges->io_end += 1; - if (ranges->mem_end == ranges->mem_start) - ranges->mem_end += 1; + /* Interesting case is when, say, io_end == io_start, i.e. + there is no I/O behind the bridge at all. We initialize + the bridge with base=io_start and limit=io_end-1, so + in this case we'll have base > limit. According to + the `PCI-to-PCI Bridge Architecture Specification', this + means that the bridge will not forward any I/O transactions + from the primary bus to the secondary bus and will forward + all I/O transactions upstream. Exactly what we want. */ ranges->io_end = ROUND_UP(ranges->io_end, 4*1024); ranges->mem_end = ROUND_UP(ranges->mem_end, 1024*1024); - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/
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