Newsgroups: comp.os.minix
Subject: Question on low-level source code
Organization: Syracuse University, Syracuse
From: mcconnel@hydra.syr.edu (Terry R. McConnell)
NNTP-Posting-Host: hydra.syr.edu
Message-ID: <36efb8a3.0@news.syr.edu>
Date: 17 Mar 1999 09:13:55 -0500
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This question refers to the kernel source as presented in the appendix
of OSDI, 2nd Ed. 

On lines 6444-6448 in mpx386.s, the contents of 5 memory locations are
pushed on the kernel stack just before a call to the label _exception. 
The latter label is the entry point to the exception routine implemented in
C in the file exception.c. After the call returns (if it ever does,) the
stack is cleaned in the usual way following a call to a C-function from
assembler. It looks as if a C-function with the following prototype
is being called:

void exception( int vec_nr, int trap_errno, int old_eip, 
			int old_cs, int old_eflags);

Indeed, the comment on lines 6449-6450 supports this interpretation. 

However, the actual prototype of exception is

void exception( int vec_nr );

I.e, 4 of these variables are never used. Am I missing some subtle point
here, or is this just cruft from an earlier version?

-- 
************************************************************************
Terry R. McConnell   Mathematics/304B Carnegie/Syracuse, N.Y. 13244-1150
trmcconn@syr.edu                            http://barnyard.syr.edu/~tmc 
************************************************************************
