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Question Accessing mapped memory of a cardbus pc-card 

Forum: PCMCIA driver development
Date: 1999, Nov 19
From: Patrick Osterloh p_osterloh

Hi folks!

I wondered if there is an other possibiliy of accessing
the mapped memory of a cardbus pc-card than writing/reading
to/from the device node (e.g /dev/cbmem0s1). The reason
for my question: I developed a CardBus PC Card that
implements a 32 MByte memory. When I write a 32-bit data
word to the device node (/dev/cbmem0s1), the data appears 
on the CardBus in two consecutive 16-bit memory transfers.
Im not sure, wether the socket controller (TI 1131) or 
file handling in the operating system is responsible for
splitting one 32-bit transfer into two 16-bit transfers.
Id like to write the 32-bit data directly into the 
mapped memory of my CardBus card, but I actually dont
know how to manage it. I already tried something like

extern volatile u_int *mem_start = 0xa0000000;
*memstart = 0x12345678;

but without succes, since the second line produces a
segmentation fault.

Perhaps someone of you out there has a solution for this
problem? 

Regards

Patrick

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1. None The memory_cb driver is not very bright by David Hinds, 1999, Nov 19

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