James,
Yes it is an actually video card and I am using fbcon. In my user space
process I have no problem mapping the memory and using it via a pointer.
However in the rtlinux module, I tried mmap (which was successful) and then
once I accessed the pointer the kernel complained.
Are you implying that instead of using mmap on /dev/mem in the rtlinux module
I should be using /dev/fb0 and then do a mmap on that. Someone suggested
using
ioremap in the module but that appears to act on io space which is not what
I want.
Thanks for the help
Adam
At 10:02 AM 11/4/99 -0500, James Simmons wrote:
>
>Are you working with a actual video card? If so what video card our you
>working with? Are you familiar with fbcon ? This provides a standard
>interface to mode setting video hardware. In fbcon we store both the
>physical address and virtual address in a data structure (fb_info). The
>physical address is what you get from the bus. Now each process has its
>own virtual address space. Thats what mmap does. In order to do this you
>need a ioremap function that maps the physical address to the virtual
>address of the process. Usually that function is in a mmap function
>defined for a driver.
>
>"We've all heard that a million monkeys banging on a million typewriters
> will eventually reproduce the entire works of Shakespeare. Now,
> thanks to the Internet, we know this is not true. It made something
> better, linux :)"
>
>On Tue, 2 Nov 1999, Adam Meyerowitz wrote:
>
>> Hello,
>>
>> Lets say I have a device (like a vga card), that maps its memory into the
>> processor
>> address space. Lets say the address is 0xe2000000. How can I write to
>> that address
>> from a rtlinux module. Can I simply assign a pointer to that address and
>> write to
>> it or do I have to do some other things?
>>
>> Thanks
>> Adam
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