How to manage 2 memory areas for offscreen allocations?

Alberto Mardegan mardy at
Mon May 22 12:09:03 PDT 2006

Hi all!
  I've begun developing a kdrive driver for the ATI Imageon 100, and
I've a (hopefully minor) problem to solve.
This device has 384KB of internal memory (suitable for 320x240), and can
make use of external SDRAM for higher resolution.  In the Sharp Zaurus,
this external memory amounts to 2MB, and it's used for a 640x480
Hence, I have two pools for offscreen memory: the internal (and faster)
384KB and the external 2MB (less the visible framebuffer area).
Since fbdev uses external memory, kdrive offscreen allocation routines
take external memory into consideration.  The faster 384KB of faster
internal memory are not used at all.

I had a look at kdrive sources, and I don't think current memory
allocation routines can handle my situation, neither in EXA.

So, what choices do I have? I know it's quite ackish, but the only
solution I've though of is allocation another KdScreenInfo structure, to
be used just for memory allocations.

Anyone ever had to face a problem like this? Would you ever accept a
patch to kdrive that allows for more than one memory block to be used as
pool for offscreen memory, optionally with some priority rule?



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