I am looking at a lot of different versions of the kernel source (1.x,
2.2, and 2.4) as I am trying to understand the kernel as a whole. In
the early versions of the kernel (1.x)
In the scheduler init; the bottom half timer routine is defined
bh_base[TIMER_BH].routine = timer_bh;
bh_base[TQUEUE_BH].routine = tqueue_bh;
In the system_call function, this bottom_half routine is defined:
handle_bottom_half:
call _do_bottom_half
And then in irq, bottom half is defined.
asmlinkage void do_bottom_half(void) {}
And then, I may use the bottom half routine with a block device driver
like the floppy driver to turn off the motor.
My question; why would the bottom half routines like the timer bottom
half get associated with a system call? E.g. if I call sys_fork,
"fork"? which will in turn call the system_call; bottom half will get
called and then call the timing routines. It seems like the timing
routines should get invoked by the timing interrupt?
How do the bottom half routines work, especially as it relates to
timing routines.
--
Berlin Brown
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