how to do page level mem alloc in freebsd kernel?
John Baldwin
jhb at freebsd.org
Thu Jul 15 12:34:41 UTC 2010
On Thursday, July 15, 2010 6:28:53 am kalash nainwal wrote:
> Hi,
>
> I want to allocate one (or more) pages in kernel space.
> I'm not sure what is the api in freebsd (something which
> is similar to __get_free_pages() of linux).
>
> Would malloc(4096, ...) guarantee that the returned
> address is aligned on page boundary?
Well, malloc(PAGE_SIZE) will align it on a page boundary. :) malloc(4096)
will be aligned on a 4096-byte boundary if PAGE_SIZE is >= 4096. My
understanding is that objects returned from malloc() are aligned to the
smallest power-of-2 value >= the requested size up to a page. Allocations
larger than a page are page aligned. So a malloc of 24 bytes or 32 bytes is
32-byte aligned for example.
--
John Baldwin
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