Issue
I am working on developing a block driver in linux. The requirement is to allocate a huge chunk of memory(example more than 128KB, 2MB or 8MB or so...), divide the memory into small chunk and sent it through scatter-gather list. The scatter gather entries will be controlled by the user application.
I know there is a strict limitation of memory available in kernel. How can I achieve this at the kernel. Any help is highly appreciated.
Solution
You can use vmalloc to allocate from virtual memory. This way, you can have all the memory you want (capped by the amount of memory there is).
From mm/vmalloc.c:
/**
* vmalloc - allocate virtually contiguous memory
* @size: allocation size
* Allocate enough pages to cover @size from the page level
* allocator and map them into contiguous kernel virtual space.
*
* For tight control over page level allocator and protection flags
* use __vmalloc() instead.
*/
vmalloced memory can be freed with, you guessed it, vfree.
Answered By - Shahbaz
