Re: Mapping memory between kernel and user space

From: Ankita Garg
Date: Wed Feb 16 2011 - 00:09:59 EST


Hi,

On Tue, Feb 15, 2011 at 12:15:08PM -0500, Sri Ram Vemulpali wrote:
> As was suggested I started reading chap 15v from LDD. I ran more into
> confusion state.
>
> I know that virtual address(process space), linear address
> (segmentation) and physical address. And how are they resolved from
> virtual to physical.
> But coming to kernel they distinguish logical address from virtual
> address. What is the main difference.
> Also, they emphasize on high memory and low memory. Why can not high
> memory can be mapped in to kernel completely.
> Why is that kernel has less visibility of complete space available on RAM.
> Linux MM is it a very specific implementation of linux, or Is that a
> traditional implementation.
>

You may want to go through the literature available on the VM subsystem.
Especially, Mel Gorman's book:

http://ptgmedia.pearsoncmg.com/images/0131453483/downloads/gorman_book.pdf

> what is very minimal implementation of MMU for real time systems.
>

Linux VM subsystem for the RT kernel is not different from traditional
one. The application has to ensure that it pins/locks its pages during
execution.

> Thanks in advance.
>
> --Sri.
>
> On Tue, Feb 15, 2011 at 12:54 AM, Ankita Garg <ankita@xxxxxxxxxx> wrote:
> > On Wed, Feb 09, 2011 at 06:45:42PM -0500, Sri Ram Vemulpali wrote:
> >> Hi all,
> >>
> >>   How do I map some space between kernel and user space. Can anyone
> >> point me in to right direction. I was trying to map the packets from
> >> my netfilter function to kernel user space, to avoid over head of
> >> copying. Thanks in advance.
> >>
> >
> > You can take a look at remap_pfn_range() routine when implementing mmap
> > in your driver.
> >
> > --
> > Regards,
> > Ankita Garg (ankita@xxxxxxxxxx)
> > Linux Technology Center
> > IBM India Systems & Technology Labs,
> > Bangalore, India
> >
>
>
>
> --
> Regards,
> Sri.

--
Regards,
Ankita Garg (ankita@xxxxxxxxxx)
Linux Technology Center
IBM India Systems & Technology Labs,
Bangalore, India
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/