how to use the memory allocated in kernel?

Hi ,

On Wed, Apr 18, 2012 at 12:44 AM, ??? [off-list ref] wrote:

Hi everyone,

there are some functions can alloc memory in kernel, but it seems that I
cannot use it directly. Here is my code:

static int mytest_vm(){

??????? struct vm_struct *v_start;

??????? v_start=alloc_vm_area(PAGE_SIZE,NULL); //the kernel api has changed,
I don't understand why there is a second parameter
??????? if(v_start==NULL){
??????????????? printk("cannot alloc page\n");
??????????????? return -1;
??????? }

??????? sprintf((char *)v_start->addr,"this is a test.\n");
??????? printk("after sprintk:%s",(char *)v_start->addr);

??????? free_vm_area(v_start);

??????? return 0;
}
module_init(mytest_vm);

but it just got a kernel Oops. Can anyone explain this to me? Thanks very
much!

If my understanding of things is correct, this just allocates virtual
space. That virtual space isn't backed by any physical pages.

The normal kernel allocators are things like kmalloc and vmalloc.

-- 
Dave Hylands
Shuswap, BC, Canada
http://www.davehylands.com