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 {[email protected] || [email protected] }
---
> Failure is not an option; it is included with every Microsoft product.
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" <[email protected]>
Newsgroups: fa.linux.kernel
To: <[email protected]>
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 {[email protected] || [email protected] }
> ---
>> Failure is not an option; it is included with every Microsoft product.
>
> -
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