how to reserve memory in linux?

[Ming Liu]

Dear Rahul,

>why do you think so ?
>Can't you give the physical address of the allocated memory from 
>linux
>kernel to peripheral's DMA.?
>Unless you need to hardcode the physicall address i hope
>virt_to_phys(kmalloc_address) can be given to DMA.
>Sorry if i am still wrong in understanding your requirement.
>

In fact, I have considered this method before. Just to dynamically allocate 
such a memory buffer and then tell the peripheral its physical address for 
accessing. However, because I really know little about the memory 
management in Linux, so I am not sure if the following question could be 
guaranteed:
Q. When I dynamically allocate a large amount of memory, I am not sure if I 
can allocate a physically continous large amount of memory. For the 
peripheral, it hopes the continous physical address, unless it has 
scatter-gather function. 

I think I must dig deeply into LDD memory management chapter to find the 
answer. :)

Of course, I appreciate your idea and suggestion. This is really a 
candidate method to solve my problem.

Thanks a lot.
Regards
Ming

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