Path: utzoo!utgpu!water!watmath!clyde!rutgers!umd5!uvaarpa!mcnc!gatech!hao!noao!arizona!lm
From: lm@arizona.edu (Larry McVoy)
Newsgroups: comp.unix.wizards
Subject: BSD internals/ether/software intrs
Message-ID: <3522@megaron.arizona.edu>
Date: 21 Jan 88 21:14:36 GMT
Reply-To: lm@megaron.arizona.edu.UUCP (Larry McVoy)
Organization: U of Arizona CS Dept, Tucson
Lines: 24

Hi there-
	I need some info about the BSD kernel and I'm too lazy to look.  What I
    want to know is

    a) when the ethernet driver takes an intr and gets to the point it has the
       data in its grubby little paws - does it just enqueue it?  The path
       I found (4.3 Mt Xinu BSD) was deintr/derecv/deread (I think) and the 
       last routine did a IF_ENQUEUE which does some stuff that looks like it's
       setting up a software interrupt.  The question is: does it put the data
       on a queue and let "someone" know, and then return?  It doesn't do
       anything with protocols (IP et al) right then (in interrupt context)
       does it?
    
    b) How do software interrupts in the BSD kernel work.  I don't mean user
       level signals, but kernel level signals.  When & how do they get 
       delivered?  If process A is in the kernel (intr) recieving a packet 
       that is destined for who knows who, when does the protocol code get
       executed?  Who is the cpu time charged to?

Thanks much (even if you tell me to take my own advice),

-- 
Larry McVoy	lm@arizona.edu or ...!{uwvax,sun}!arizona.edu!lm
		Use the force - read the source.