[SOLVED] Allocating memory with "get_free_pages(flag,order)"

Rezo · 07-01-2013, 09:04 AM

Good day to everyone,
sorry for my english
i'am new to linux, linux kernel and so on,

i'am trying to understand how to allocate physically contiguous up to 2 MB, but dont understand how to use "get_free_pages" function to allocate it, if anyoane has an example, or know how to use it, or maybe some other functions, please reply. I'am trying to use it for DMA.

thanx for replying

padeen · 07-01-2013, 11:50 PM

First up, I've never written a device driver. However, the documentation at http://kernelnewbies.org/KernelMemoryAllocation seems to indicate you should not be using get_free_pages(), but instead the DMA memory routines. See the section titled DMA at the bottom of the page.

Also the DMA API docs at https://www.kernel.org/doc/Documentation/DMA-API.txt mention you should not be using get_free_pages.

Rezo · 07-02-2013, 03:26 AM

thanx for replying padeen,

I already write a basic driver, now i'am trying wo work with DMA, and reading some documentation i just saw this function, but it's seems that nobody use it. there are many documentation on DMA, but when it comes tu use it its very complicated

, like trying to crack a password without passcracker.

Rezo · 11-21-2013, 05:12 AM

found more useful:
kmalloc - for allocating memory up to 128 KB
and
vmalloc - for big area memory