Mapping of Device Physical Address to Kernel Virtual address

[Prabhu nath]

Thanks for your reply. Plz see inline

On Tue, Jul 10, 2012 at 11:50 AM, Dave Hylands <dhylands at gmail.com> wrote:

> Hi Prabhu,
>
> On Mon, Jul 9, 2012 at 9:56 PM, Prabhu nath <gprabhunath at gmail.com> wrote:
> > Dear All,
> >
> >                    Is it possible to map a physical address of a device
> to a
> > known Kernel virtual address. I know about ioremap_xxx (...).
> > which will map a physical address of a device to a kernel virtual address
> > allocated by ioremap_xxx(...).
> >
> > For E.g. I have a device whose physical address range is 0x80008000 to
> > 0x80008FFF.
> >              Is it possible to map this device physical address to a
> known
> > virtual address range 0xF0008000 to 0xF0008FFF.
>
> About the only way to do this is to use static mappings. I was under
> the impression that static mappings are on the way out, and that
> dynamic mappings are required when using device tree.
>
> An example of using static mappings can be found here:
>
> http://lxr.linux.no/linux+v3.4.4/arch/arm/mach-integrator/integrator_ap.c#L88


   In this file, how did they mark IO_BASE. Is the allocator not aware of
this region in the kernel virtual address space. ?

>
>
> > My hardware configuration has 128 MB of system RAM which will have been
> > MAPPED to the Kernel virtual address from 0xC0000000 to 0xC7FFFFFF
> >
> > Also is it possible to configure the vmalloc kernel virtual address
> region
> > to a fixed range of 128 MB from 0xC8000000 to 0xCFFFFFFF
>
> I believe that you can only control the vmalloc start by controlling
> the amount of SDRAM that you have.
>
> --
> Dave Hylands
> Shuswap, BC, Canada
> http://www.davehylands.com
>
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