4MB of physical contiguous memory allocation in Linux

4MB of physical contiguous memory allocation in Linux

[vyas niranjan]

HI,

   I am writing a driver whereI am trying to allocate
4MB of Physical contiguous memory. Using
__get_free_pages, I can allocate maximum of 512 pages
in Linux. Is there any way of allocating 4MB of
Physical contiguous memory in Linux??

Thanks and Regards

__________________________________________________
Do You Yahoo!?
Yahoo! Finance - Get real-time stock quotes
http://finance.yahoo.com
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/

Re: 4MB of physical contiguous memory allocation in Linux

[Martin J. Bligh]

>    I am writing a driver whereI am trying to allocate
> 4MB of Physical contiguous memory. Using
> __get_free_pages, I can allocate maximum of 512 pages
> in Linux. Is there any way of allocating 4MB of
> Physical contiguous memory in Linux??

If MAX_ORDER is 10, which it is by default, I think, you should
be able to get 2^10 = 1024 pages = 4Mb. What happens if you
do an order 10 allocation? Or turn MAX_ORDER up a little, and
see what happens ...

M.

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/

Re: 4MB of physical contiguous memory allocation in Linux

[Martin J. Bligh]

>>    I am writing a driver whereI am trying to allocate
>> 4MB of Physical contiguous memory. Using
>> __get_free_pages, I can allocate maximum of 512 pages
>> in Linux. Is there any way of allocating 4MB of
>> Physical contiguous memory in Linux??
> 
> If MAX_ORDER is 10, which it is by default, I think, you should
> be able to get 2^10 = 1024 pages = 4Mb. What happens if you
> do an order 10 allocation? Or turn MAX_ORDER up a little, and
> see what happens ...

Hmmm .... looking at a little of the code, seems like MAX_ORDER is
just really badly named, and it's the maximum order + 1. 
Turn it to 11 ... that should fix it.

M.

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/