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Re: Axcessing *R_PAR1_CTRL_DATA from programs under Linux.



On Mon, Apr 30, 2001 at 01:52:11PM +0200, Jonas Aaberg wrote:
> 
> On 2001.04.30 12:13:05 Jonas Aaberg wrote:
> > 
> > On 2001.04.30 12:24:47 Mikael Starvik wrote:
> > > The internal registers are not available from userspace
> > > (I don't think you can find any platform with a MMU
> > > that lets you tamper with hardware registers directly).
> > > If you need to access the registers you should do it
> > > from kernel space e.g. from a device driver.
> > I thought so too, but I found it quite nice to be able to
> > do that in userspace on the old Etrax, so I hoped there
> > was a way to do that. 
> > 
> > Thanks for your answer.
> 
> But on a second thought, for example the X server must be
> able to change internal registers to switch to graphic mode.
> So I think it can be possible from a program running with
> chmod +s, owner root to change internal registers, somehow.
> Could it be possible to memory map the interal register area
> as shared memory? Just an idea, mabye it is impossible.

PS: Forgot to mention there is /dev/port which represents I/O ports you can
use calls open, write, read on a fd, you can do lseek to the port offset and
and do a read/write on the fd, avoid using streamed IO f*** functions
because of buffering.

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