How can I use a specific ram address?

[Matthias Lange]

On Tue, Mar 18, 2014 at 03:54:59PM +0100, Christian Helmuth wrote:
> Hello,
> 
> On Tue, Mar 18, 2014 at 09:22:20PM +0800, 吴若凡 wrote:
> > I am now facing a problem that I want to use a specific ram address [0x0,
> > 0x2000000), because there is a hareware on board using it, I have to write
> > data to this specific ram region and my hareware will read this region to
> > work.
> > 
> > I have moved foc kernel address to 0x2000000, and also used
> > Attach_io_mem_dataspace to reflect physical address [0x0, 0x2000000) in my
> > driver, but I failed to drive my hareware.
> > I guess maybe the data haven't been written to this ram region correctly.
> > Is  Attach_io_mem_dataspace suitable for this case? If NOT, how can I do ?
> 
> Genode depends on sigma0 to detect RAM regions. Sigma0 itself depends
> on bootstrap's information. So, I think you have to figure out how to
> configure bootstrap to exclude (or better to _not_ include) [0x0,
> 0x2000000) from RAM. Afterwards, Attached_io_mem_dataspace should work
> as expected. Do you have a serial log of bootstrap's boot messages?

When you build bootstrap you can specify the RAM_BASE either by providing it
on the cmdline or through menuconfig (choose 'Custom Platform'). Another
important parameter is RAM_SIZE_MB.

Matthias.