From: David Hawkins <dwh@ovro.caltech.edu>
To: Kumar Gala <galak@kernel.crashing.org>
Cc: "Wyse, Chris" <chris.wyse@windriver.com>,
+linux-embedded <linux-embedded@mail.wrs.com>,
linuxppc-embedded@ozlabs.org
Subject: Re: Memory mapping PCI memory region to user space
Date: Thu, 23 Mar 2006 09:12:03 -0800 [thread overview]
Message-ID: <4422D6E3.1010407@ovro.caltech.edu> (raw)
In-Reply-To: <204E7000-3E88-4497-86C0-5AF786D72F75@kernel.crashing.org>
> Why don't use the mmap file exposed by sysfs so you dont have to
> write your own code?
>
> See Documentation/filesystems/sysfs-pci.txt. But effectively down
> under /sys/bus/pci/devices/[domain:bus:dev:func]/ you will get
> resource[0..N-1] that corresponds to each BAR on the device. This is
> a mmap file to access that region.
Hi Kumar,
Most likely he didn't know about it, I didn't :)
When I was testing the Yosemite board as the host, I found
that I could set the endian flag on the mmapped page, which
then made the PCI device registers read as 32-bit quantities
read back with the same layout under both x86 and PPC
hosts.
So, if someone planned on using that 'feature', that would
be a reason for writing your own mmap() implementation.
I didn't see any option in the sysfs file for setting that
page flag (but, I didn't look around in other sysfs files).
Thanks for the pointer to the sysfs node!
Cheers
Dave
next prev parent reply other threads:[~2006-03-23 17:10 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-03-23 14:21 Memory mapping PCI memory region to user space Wyse, Chris
2006-03-23 15:44 ` Kumar Gala
2006-03-23 17:12 ` David Hawkins [this message]
2006-03-23 17:19 ` Kumar Gala
2006-03-23 17:43 ` Mark Chambers
2006-03-23 17:54 ` David Hawkins
2006-03-23 19:55 ` Mark Chambers
2006-03-23 20:26 ` David Hawkins
2006-03-23 17:46 ` David Hawkins
2006-03-27 8:02 ` Phil Nitschke
2006-03-27 16:05 ` David Hawkins
2006-03-28 4:21 ` Phil Nitschke
2006-03-28 4:55 ` David Hawkins
2006-03-28 6:44 ` Phil Nitschke
2006-03-28 16:35 ` David Hawkins
2006-03-27 16:18 ` Kumar Gala
2006-03-29 2:26 ` Phil Nitschke
2006-03-23 17:04 ` David Hawkins
-- strict thread matches above, loose matches on Subject: below --
2006-03-23 19:52 Wyse, Chris
2006-03-23 20:01 ` Kumar Gala
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