help

[shin_ta]

I have some questions about the design and implementation of the FreeBSD operating system
1.          FreeBSD used System call, Hardware interrupt, Hardware trap, and Software-initiated trap to entry into the system kernel. What is the detailed operation and why FreeBSD design by this way?
 
2.          In FreeBSD 5.2, interrupt has its own context stack, what are the influences to each aspect of the operating system?(like bottom half of kernel, top half of kernel …)
 
3.          What is the basic function of the signal? Which main data structures are about signal? Which procedures are related in signal?
 
4.          Why signal handler routine design in user-level but not in kernel-level?
 
5.          After the system call completes, the system-call exit code first checks for a posted signal, after checking for posted signals, the system-call exit code checks to see whether any process has a priority higher than that of the currently running one. Why FreeBSD do this check at this time?
 
6.          The ULE scheduler was developed as part of the overhaul of FreeBSD to support SMP. Why the ULE scheduler relatively suitable for the SMP system than 4.4BSD timeshareing scheduler.
 
7.          FreeBSD uses pager to manage the memory. Different memory objects have different pager to deal with. Why FreeBSD designed by this way?