Path: utzoo!mnetor!uunet!husc6!bloom-beacon!gatech!hubcap!ncrcae!ncr-sd!greg
From: greg@ncr-sd.SanDiego.NCR.COM (Greg Noel)
Newsgroups: comp.unix.questions
Subject: Re: Stack Direction -- Any War Stories?
Message-ID: <1962@ncr-sd.SanDiego.NCR.COM>
Date: 21 Dec 87 21:15:06 GMT
References: <205@ksr.UUCP>
Reply-To: greg@ncr-sd.SanDiego.NCR.COM (Greg Noel)
Organization: NCR Corporation, Rancho Bernardo
Lines: 17

In article <205@ksr.UUCP> benson@ksr.UUCP writes:
>Has anyone any war stories of porting an application across a stack
>direction boundary and having it break due to pointer magnitude comparisons
>or other difficulties?

How about vi?  When we were porting Unix to a processor not only had a stack
that grew upward, but also had the stack in low memory (well, below the heap),
we found, after a long series of seemingly random problems, that the routine
to free memory attempted to see if the address of the item to be freed was
above or below one of its parameters and only called free() if the address
was lower.  Therefore, in our case, it tried to free() things on the stack
and never freed things on the heap.  Obviously, eventually, things got
trashed in strange ways and it would punt.

This was some time ago; the problem may have since been fixed.
-- 
-- Greg Noel, NCR Rancho Bernardo   Greg.Noel@SanDiego.NCR.COM  or  greg@ncr-sd