Help testing arora,qt5 and sdl examples on RaspberryPI

[Norman Feske]

Hello Reinier,

> I have switched to Genode's release 14.08, prepared again the ports and
> compiled the examples in the same way, but when try to test it on RPI,
> only the colored screen again.
> Someone have tested successfully this examples on RPI hardware? I have
> tested successfully the Demo example.

the SDL and Qt5 examples are indeed not expected to work on the
Raspberry Pi out of the box. Most run scripts still lack two things that
are important for the RPi, namely the platform driver and the USB HID
driver. Those components are included in the 'os/run/demo.run' script
but are lacking in many others such as the 'libports/run/sdl.run'.
However, you should still get serial output in any case. Normally, the
serial output gives enough indications about the missing pieces. Given
the demo.run script as example, complementing the other run scripts with
the missing pieces should be straight forward.

Has the switch to version 14.08 resolved the build problem?

As another heads-up warning regarding the Rpi, the USB driver is still
not perfect. There are two issues. First, the keyboard is not working
reliably unless you set the number of used host channels to 8 instead of
2 using the 'dwc_param_host_channels_default' define in
<genode-dir>/contrib/dde_linux-<hash>/src/lib/dde_linux/drivers/usb/host/dwc_otg/dwc_otg_core_if.h.
Second, the USB driver draws an enormous amount of CPU time because it
has to issue USB start-of-frame (SOF) transactions every microframe
(that is every 250 microseconds). So when the USB driver is running,
there is hardly any CPU time left for the other processes. On Linux,
this problem has been somehow fixed by the so-called FIQ optimization. I
am still pondering about the best way to relieve this issue when using
the base-hw kernel.

Best regards
Norman

-- 
Dr.-Ing. Norman Feske
Genode Labs

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