Re: mem=XXXM ioremap DMA

Eric Nuckols wrote:

quoted

Eric Nuckols wrote:
    

quoted

in my driver, I'm calling
my_virt_address =   ioremap( 0x1F800000, 0x800000  );
my_bus_address = virt_to_bus( my_virt_address );

      

You can't use virt_to_bus on address returned by ioremap AFAIK.

I think you could do
my_bus_address = virt_to_bus(phys_to_virt(0x1f800000));

Altough it slightly misuse the functions ... but that should work.


        Sylvain

    

If I use this approach in a driver, won't I still need to use the ioremap 
function to make sure the kernel does not reassign the virtual addresses to 
some other physical memory locations?

mmh, I wasn't clear :
You must do :

my_virt_address =   ioremap( 0x1F800000, 0x800000  );
my_bus_address = virt_to_bus(phys_to_virt(0x1f800000));

The virtual address returned by phys_to_virt won't be really valid ... but it
will be good enough for virt_to_bus. In the end, it will just do
PCI_DRAM_OFFSET + 0x1f800000;


Sylvain