Hi,

I wrote a small kernel module that defines and exports bfree() and 
bmalloc() functions. The idea is to use this kernel module as a 
replacement for big physcial area kernel patch.

For example, zoran kernel driver relies on the big physical area API for 
v4l (used for video-in-a-window) to work. While the driver will compile 
and load with a non-patched kernel, v4l will not work reliably without 
big physical area support since the chip needs about 2megs of contiguous 
memory to display in a window. This means one really has to use a 
patched kernel.

This module removes this requirement and allows v4l to work reliably 
with a non-patched kernel. The idea is to load the module from initrd or 
right after boot. I have used __get_free_pages() and mem_map_reserve() 
to pre-allocate the memory.
I have left the user-mode code that I used to debug allocation and 
garbage collection.  Compiled into a user-space program, the code will 
allocate/free random chunks from a pre-allocated space and print out the 
used list.

Comments?

Questions:
1) On  a 256 MB machine, I was able to pre-allocate 512 pages using 
__get_free_pages(...,get_order(size)). It is enough for one card, but 
not for more. Any ideas on how to pre-allocate more?
2) __get_free_pages(...,get_order(size)) can be used to pre-allocate 2^n 
contiguous pages (2,4,16,...512, ...., 1024). Can I use something else 
from a kernel module to request a number that is not  2^n  (say 750)?

-- 
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Constantine Gavrilov
Linux Leader
Optibase Ltd
7 Shenkar St, Herzliya 46120, Israel
Phone: (972-9)-970-9140
Fax:   (972-9)-958-6099
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