Messages in this thread | | | Date | Thu, 23 Sep 2004 21:07:59 -0600 | From | Robert Hancock <> | Subject | Re: PCI Burst |
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Two things that I'd check, that the memory range shows up as prefetchable (i.e. in lspci) and also that the memory region is mapped with ioremap and not ioremap_nocache. Also, what's the region defined as in /proc/mtrr? I think it has to be mapped as write-back for burst reads to work. When the CPU reads in a cache line in that memory range from the bus, that should hopefully get passed through as a burst read on the PCI bus, but that may be chipset-dependent.
Getting PIO-mode PCI reads and writes like this to work efficiently seems a rather difficult thing to do..
----- Original Message ----- From: "Brian McGrew" <Brian@doubledimension.com> Newsgroups: fa.linux.kernel To: <linux-kernel@vger.kernel.org> Sent: Thursday, September 23, 2004 7:22 PM Subject: PCI Burst
> Running RedHat 7.3 with the 2.4.20 kernel. > > How do I enable PCI burst mode for reading and writing on the PCI bus? We > mmap 128MB per board that we install and now that we've added our > addressing to the /proc/mtrr file, we can burst on write but we're not > seeing any burst on the read. > > Any ideas? > > -brian > > Brian D. McGrew {brian@doubledimension.com || pacemakertaker@rock.com } > --- >> Failure is not an option; it is included with every Microsoft product. > > - > 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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