Path: utzoo!mnetor!uunet!husc6!bbn!rochester!udel!rminnich
From: rminnich@udel.EDU (Ron Minnich)
Newsgroups: comp.sys.amiga
Subject: a very simple question on DoIO/GetMsg/device drivers
Message-ID: <890@louie.udel.EDU>
Date: 22 Dec 87 01:59:25 GMT
Reply-To: rminnich@udel.EDU (Ron Minnich)
Distribution: na
Organization: University of Delaware
Lines: 29

I have a very simple question and i think a very simple problem
involving internet.device. Here is the scenario:
Telnet does a SendIO(Request).
internet.device gets the request, and adds the request to a List.
Later on, internet.device does the IO. It gets the request, and
all looks good. the request is acted on (in this case, a recv_tcp).
Then, internet.device does a ReplyMsg(Request). A Message is the 
first element of the structure, and the structure does conform
to all the rules about what has to be in the front and in what 
order. 
   Telnet gets the news. It does a CheckIO(Request), which returns
non-zero value. It also does a WaitIO for grins, and gets a zero
back. Then the fun begins. The port in this case is called tcpinp.
If i look at tcpinp->MsgList (not the exact name), the lh_Head
points to Request, and lh_TailPred points to Request. But a 
GetMsg(tcpinp) returns a 0! How can this happen?
  Next, after the GetMsg call, a look at the MsgList structure
shows that lh_TailPred points to lh_Head, and lh_Head points to lh_Tail.
So it looks like the list got emptied, but ... if i do a CheckIO, 
it still returns a non-zero value! What conditions cause a CheckIO
to return non-zero? Is the Flags element of a request what is looked
at by CheckIO? I thought it was the ReplyPort that really mattered. 
  Then, to top it off, if i do a SendIO(Request), the whole machine
locks up tight as a drum. 
  Now i am sure i am doing something quite dumb. Can anyone tell 
me what to look for?

-- 
ron (rminnich@udel.edu)