[ECOS] RedBoot serial rx interrupts

[Grant Edwards <grante at visi dot com>]

I've got RedBoot running fine without network support.  It's
using polled serial I/O: the individual serial Rx interrupts
are unmasked but the global interrupt mask is set.  

[Why are interrupts being unmasked when polled I/O is being
used?]

When I add network support, the global interrupt mask is
cleared; cyg_hal_plf_serial_isr then consumes all of input
data.  RedBoot is still calling cyg_hal_plf_serial_getc() to
try to read input, but it never sees any because it's all being
consumed by the interrupt routine.

Can anybody point me to something that explains RedBoot's use
of interrupts?

Is the network stack interrupt driven?

Why does including network support clear the global interrupt
mask bit?

When is serial I/O interrupt driven?

-- 
Grant Edwards
grante@visi.com