The new 'dde_linux' repository will host device drivers ported from the
Linux kernel. In contrast to the original 'linux_drivers' repository,
'dde_linux' does not contain any 3rd-party source code. To download the
Linux kernel source code and extract the drivers, execute the 'make
prepare' rule of the top-level Makefile. The initial version of the
'dde_linux' repository comes with an USB driver. The porting methodology
follows the path of the Intel GEM port. Instead of attempting to provide
a generic Linux environment that works across drivers, each driver comes
with a specially tailored DDE.
The DDE consists of Genode-specific implementations of Linux API
functions as declared in 'lx_emul.h'. Most of these functions are
dummies that must merely be provided to resolve dependencies at the
linking stage. They are called by unused code-paths.
As of now, the USB driver support UHCI, EHCI on the x86_32 platform. I
exposes USB HID devices and USB storage devices via Genode's input-session
and block-session respectively.
The USB driver is accompanied with two run scripts 'run/usb_hid.run' and
'run/usb_storage.run'.
The build system overlays multiple source trees (repositories) such that
they can shadow libraries and include search paths. This patch extends
the shadowing concept to build targets. Furthermore, it streamlines the
build stage for generating library depenencies, reducing the processing
time of this stage by 10-20 percent. Fixes#165.
