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<br>
Hi.<br>
<br>
We've run into an .... interesting (and frustrating) occurance recently
while testing<br>
out a new board (and BSP). We were wondering if anybody has seen
anything <br>
like this.<br>
<br>
A description follows:<br>
<br>
We wrote some simple drivers/modules to mmap() FPGA registers to user
space.<br>
At the moment, for testing, we reserve the upper x-MB of RAM, and
mmap() there, instead.<br>
<br>
We open 4 such devices, and mmap() 64KB of space (memory, in this case)
for each.<br>
Accessing the first device opened & mmapped was fine. But
accesssing the 2nd device<br>
yielded some odd behavior. We could read and write the first and 3rd
4K regions fine, but<br>
if we <i>read</i> from the 2nd one (at offset 0x1000) before we wrote
to it, we get a segmentation<br>
fault. If, however, we wrote first (to the 2nd region), then things
were OK.<br>
<br>
Addendum: With the real device, this same behavior happens at the 10th
4-KB region of the device.<br>
Without any of the others mmap()-ed. If we mmap() just that 4-KB
region, things are fine. We<br>
can access the region with ioremap() in the driver w/o issues.<br>
<br>
We are running on an MPC8349-E.<br>
<br>
Any thoughts or ideas?<br>
<br>
<br>
vti<br>
<br>
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