Path: utzoo!attcan!uunet!munnari!otc!metro!ipso!runx!brucee
From: brucee@runx.ips.oz (Bruce Evans)
Newsgroups: comp.os.minix
Subject: Re: Minix Library Reentrancy
Message-ID: <1532@runx.ips.oz>
Date: 22 May 88 14:47:10 GMT
References: <433@moncsbruce.oz>
Organization: RUNX Un*x Timeshare.  Sydney, Australia.
Lines: 13


The author of the original article informed me about the following
fundamental problem:

It is impossible to pass messages on the stack to the kernel, since the
kernel explicitly checks (in proc.c/mini_send()) that all user messages
are in the DATA segment (as opposed to the STACK segment).

This seems like an oversight, since stack and data are much the same in C.
Of course, an extra check to allow the stack segment will mainly slow
down the kernel. Is there anything more to it than this?

Bruce Evans
Internet: brucee@runx.ips.oz.au    UUCP: uunet!runx.ips.oz.au!brucee