Some questions about high memory

[loody]

hi all:
I am trying to write a driver for my block device which dma support
high memory copying.
I have register my device as "blk_bounce_any".
But my driver cannot see block layer pass high memory to me so far.

Is there any user/kernel test program which will purposely send high
memory for driver to use?
or is there any flag when opening a file in user mode that will use high memory?

-- 
Thanks for your help in advance,