sumthinelse
civ investigator
Originally posted by starlifter
A sniffer is a software that monitor network packets, and identifies certain patterns, typically addresses, that pass.
Don't know, but a guess would be a NOP. I still have an original 486 that was defective. I never had it replaced following the 486 defect mess.
Thanks starlifter. A Sniffer is one example of a protocol analyzer. Also called network monitor, as you said. Suppose you have a problem between client and a server but you don't know which machine the problem occurs on. By using a protocol analyzer you can often see which machine has the problem and thereby cut your debug time dramatically.
This is the answer for question #3.
the cli (clear interrupts) flag protects a critical code section, for example, inside a semaphore. You have a routine that has such a critical section, but you don't know if the routine that called your routine already disabled interrupts. On the 286, people used to do this
pushf (push the flags register, including the interrupt flag)
cli (disable interrupts)
.... (critical section)
popf (pop the flags register. now I have restored the interrupt state that was in effect before the pushf.
However, the 386 had a bug in the popf that allowed an interrupt to occur, and this caused much wailing and gnashing of teeth.
solution - replace popf with:
push cs
push ip
iret (interrupt return - pops ip, cs, and flags in one instruction)
OK, now back to your question....