linux-kernel - Re: Reading a physical memory location

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Date:	Tue, 10 Jul 2007 14:12:22 -0400
From:	vraghavan3@...l.gatech.edu
To:	Nobin Mathew <nobin.mathew@...il.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: Reading a physical memory location


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?

-- Veena



Quoting Nobin Mathew <nobin.mathew@...il.com>:

> Hi,
>         If you know the physical address, then you get virtual address
> from that physical adress by using ioremap().
>
> Then you can use readl(virtualaddress) to read the string from there
>
> Nobin Mathew
>
> On 7/10/07, vraghavan3@...l.gatech.edu <vraghavan3@...l.gatech.edu> wrote:
> >
> >
> > --
> > Hey all,
> >
> > I know the physical address of a string which is loaded into flash memory.
> I
> > want to read the string at the known physical memory location from within a
> > kernel module. I initially tried reading the "/dev/mem" file using open(),
> > lseek() and read(). But I guess its not possible to call these functions
> from a
> > kernel module.
> >
> > Is there some way of reading the contents of this physical memory location
> from
> > within a kernel module?
> >
> > Thank You
> > Veena
> > -
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