- no need to splhi() in timerset, always called with
interrupts off.
- make timerset always update the period (next == 0)
- remove period update in fastticks(), simplify
delta calculation.
introduce cpushutdown() function that does the common
operation of initiating shutdown, returning once all
cpu's got the message and are about to shutdown. this
avoids duplicated code which isnt really machine specific.
automatic reboot on panic only when *debug= is not set
and the machine is a cpu server or has no display,
otherwise just hang.
when we switch to graphics mode, we do not want graphical arcs console
to print on the screen anymore as it assumes 8bit color mode and just
messes up the screen on kernel prints.
GEVector() saves the exception return PC in Ureg.r27 which needs
to be preserved.
there should be no reason for the user to change the status
register from noted() eigther, so we now just use setregisters()
in noted() to restore previous general purpose registers. this
means that CU1 will always be off after noted() because notify()
has disabled the FPU on entry and set fpstatus to FPinactive
if it was on. once user starts using FPU again, it will trap and
restore fpu registers.
touching transmit descriptors while dma is running causes the
front to fall off. new approach keeps a counter of free
descriptors in the Ring structure that is incremented
by txintr() when transmit completed.
txintr() will clean descriptors once dma has stopped and
restart dma when there are more descrtors in the chain.
this provides basic console support using the ARC bios routines
theu uartarcs driver. and has native seeq ethernet driver which
was written by reading the 2ed devseq driver as i have no
documentation on the hardware. mmu and trap code is based on the
routerboard kernel.