[RFC PATCH 2/3] ARM: mm: add l2x0 physical address parameter to init

[Lorenzo Pieralisi]

Hi Russell,

thanks for looking at this series.

On Mon, Sep 26, 2011 at 03:51:04PM +0100, Russell King - ARM Linux wrote:
> On Mon, Sep 26, 2011 at 03:32:40PM +0100, Lorenzo Pieralisi wrote:
> > This patch redefines the l2x0_init function, and it adds a
> > parameter defining the L2 physical base address in preparation
> > for L2 resume support. The device tree init code retrieves the
> > physical address from the "reg" array and converts it to a
> > physical address pointer.
> 
> I've no idea why many people have a really dire time understanding the
> following basic fact.  I keep seeing the same things: virtual addresses
> as integers and physical addresses as pointers.

I should not have converted it to a pointer, you are right, sorry; I am not 
using it as such unless the MMU is off.

> 
> Virtual addresses are pointers.
> Physical addresses are NOT pointers but integers.
> 
> Why?  You CAN'T dereference a physical address when running in the virtual
> address space (which is the space which the kernel runs in.)
> 

Well, to be precise the kernel runs in it when the MMU is on.

By no means, the purpose is NOT to dereference it when the MMU is on and
I am not doing that.

But I agree the physical address should be an integer parameter and be
passed as so, lest someone might want for whatever reason to dereference
it when the MMU is on and unleash hell.

Thank you,
Lorenzo