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12748 Discussions

frame buffer

Altera_Forum
Honored Contributor II
‎05-12-2005 05:15 PM
1,165 Views

Hi, 

I wrote a simple frame buffer driver for my LCD controller in uClinux 2.6.9. 

My video card shares your memory with system memory.  

How can I alloc video card memory in kernel space?  

I make it with a kmalloc but when I want to point in fb memory from userspace mmap syscall don't work correctly. 

If I don't use kmalloc, mmap return a correct pointer and I can write correctly in videomemory... 

but kernel crash when alloc your structure in the same address. 

 

In my driver I've implemented ..fb_mmap() function but the kernel never use it. 

Why?
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Altera_Forum
Honored Contributor II
‎05-12-2005 08:39 PM
483 Views

Look into the function __get_free_pages(unsigned int flags, unsigned int order) -- it's described in Linux Device Drivers 3rd edition (published by O'Reilly press and supposedly freely available somewhere, but I've never found where).

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