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-   -   physical memory allocation over 4b (https://www.linuxquestions.org/questions/linux-kernel-70/physical-memory-allocation-over-4b-707973/)

protagora27 02-27-2009 08:21 AM

physical memory allocation over 4b
 
Hello folks,

I have a 64 bit dma that I have to program with 64 bit physical
address
beyond 4 gb because I have to test dma with memory allocation beyond
4 gb.
I 'm using linux x86_64 2.6.24 and I have 8 gb ram.
How can I allocate physical dma memory beyond 4gb ? In x86_64
can I use __pa to have physical address ?

I would like to find a function that returns a physical adddres beyond
4gb
and then i write phys address in dma register .

Thanks.

Drakeo 02-28-2009 02:03 AM

you know you should let people know if you are using a vanilla kernel or some distro that dose not use a vanila kernel. It is the gernel that runs the cpu so it will see and use over 4 gbas far as slackware just use the 2.6.27.7 huge smp. kernel.


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