[okl4-developer] Some questions about OKL4's driver

[kashin Lin]

Hi,

After trying to modify some codes in
"src/platform" to adapt okl4 to my target, i found i'm
confused about the driver's relationship.( my target is Davinci from TI
which has arm926ej-s and DSP inside)
the naming example works correctly on my target now. and the following are
my questions:

1. in pxa's machine.py for example:
       drivers = [timer_driver] + pxa.drivers  &
       v2_drivers = [ ("pxa250_timer", "vtimer"), ("uart_8250", "vserial"),]
    does "v2_driver" replace "driver" (so "driver" is no use) ?

2. "Timer driver" :
    what's the difference between "src/drivers/pxa250_timer" &
"src/platform/pxa/pistachio/src/timer.cc"?
    as
i comprehend, the timer in platform/ is OS timer and responds to
generate a period interrupt to
    trigger scheduling in kernel. if it's right, this seems to be a
indispensable component.
    but why okl4 still works even i
don't set the memory map address to OS timer correctly?
( i try naming example )
    what is the function of
the timer in drivers/ ? does l4 kernel use this driver? for what?

3. "UART driver" :
    what's the difference between "src/drivers/uart_8250" &
"src/platform/pxa/pistachio/kdb/console.cc"
    it seems the printf function call is based on console.cc, so the
output msgs from target through rs232
    are visible only when i set the correct memory map address to it.
    but what is the function of the uart driver in drivers/ ?

4. in src/platform/pxa/, there are some codes like irq.cc and intctrl.h
 related to interrupt controller.
    but why okl4 still works even i don't set the memory map to INT
controller's registers correctly?
    i add printf in OS timer's INT handler further, but no output shown.
   so does OKL4 not use any interrupt?

thanks for answering my questions.


best regards,

kashin lin
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