L4Linux stub drivers & L4 drivers

Adam Lackorzynski adam at os.inf.tu-dresden.de
Tue Feb 17 19:26:03 CET 2009

On Mon Feb 16, 2009 at 08:09:01 -0800, Alexander Valitov wrote:
> Adam Lackorzynski wrote:
> > 
> >> 5. And L4_PDSPBLK_DRV?
> > 
> > It's block driver for a backend server that works on (memory) dataspaces.
> > 
> Do you mean it is a kind of loop device which gives access to memory
> treating memory contents as a block device sectors? And memory is provided
> by dataspace manager with dm_mem or dm_generic interface?

Yes, basically. Block device backend storage is just memory.

> Is there corresponding L4 server available?


> Adam Lackorzynski wrote:
> > 
> >> 6. And L4_FB_DRIVER_XF86IF?
> > 
> > The counterpart to Xorg driver in the l4con package.
> > 
> Is it needed to be turned on if I'd like to start X11 server when l4con or
> dope is used?

Depends. The easy method is just to use the fbdev driver in X11 and thus
just use the (L4)Linux framebuffer. This has a few drawbacks like needed
screen refreshs but works easily. The other one is to have an X server
that knows the underlying system, i.e. has a special driver. This e.g.
does not need refreshs but needs the special X driver.

> Is it bridge between l4fb and X11 server?

Only if the X driver is used.

> There is another option that looks pretty interesting for me. It is
> CONFIG_L4_USE_L4VMM. I discovered it here:
> L4Linux configuration->Advanced options->Use L4VMM
> Help says: L4VMM can emulate hardware and provide access to virtual and
> physical host devices. For PCI, enable PCI support (choose direct access
> mode) and the required device drivers.
> Could you please tell me what is it intended for?

It's for a very experimental service that virtualizes devices, e.g. a
PCI bus or disk.

Adam                 adam at os.inf.tu-dresden.de
  Lackorzynski         http://os.inf.tu-dresden.de/~adam/

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