Re: Could convert a buffer that allocated by vmalloc to pages?

From: Kyle McMartin
Date: Tue Jan 23 2007 - 10:42:50 EST


On Tue, Jan 23, 2007 at 10:15:33PM +0800, Yu-Chen Wu wrote:
> printk(KERN_INFO "vmalloc_to_page tpage :%x\n",tpage);
> //===========info of dmesg==================
<snip>
> [ 1561.768492] page allocated:60ea9000
> [ 1561.768497] vmalloc_to_page tpage :7fcf7e18
>
> Why the page address get from vmalloc_to_page is different with the first
> page address of the vm_struct (73d65000)?
>

Memory returned by vmalloc is only virtually contiguous, not physically
contiguous. If you're allocating memory for DMA, see the interface
documented in Documentation/DMA-mapping.txt for more information.

-- Kyle
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