See this in the documentation
The returned virtual address is a current CPU mapping for the memory
address given. It is only valid to use this function on addresses that
have a kernel mapping
This function does not handle bus mappings for DMA transfers. In
almost all conceivable cases a device driver should not be using this
function
Nobin
On 7/11/07, Manu Abraham <[email protected]> wrote:
On 7/11/07, Nobin Mathew <[email protected]> wrote:
> Which is your platform ?
>
> Which processor?
>
> If you want to use physical address directly, then disable MMU. That
> is not possible in linux.
ioremap does map io memory using phys_to_virt
I thought phys_to_virt was enough to remap physical memory to virtual
http://mirror.linux.org.au/linux.conf.au/2005/cdrom-beta-1/linux-mandocs-2.6.12.6/phys_to_virt.html
>
> Nobin
>
> On 7/11/07, Manu Abraham <[email protected]> wrote:
> > On 7/10/07, [email protected] <[email protected]> wrote:
> > >
> > > Thanks for the quick reply. But I was wondering as to why I would have to map
> > > the physical address to the virtual address when I know that the string is
> > > permanently in the physical memory because its loaded into flash. Is there a way
> > > to directly read from the physical memory location? Also, do the functions
> > > ioremap() and readl(va) work when called from within a kernel module?
> > >
> >
> > Of course, if you look at almost any of the memory mapped device
> > drivers, you will find that ioremap/readl/writel is the backbone of
> > your infrastructure.
> >
> >
> > Manu
> >
>
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