Date: Fri, 19 Sep 1997 13:48:22 -0500 (EST) From: "John S. Dyson" <toor@dyson.iquest.net> To: nate@mt.sri.com (Nate Williams) Cc: dyson@FreeBSD.ORG, nate@mt.sri.com, karpen@ocean.campus.luth.se, current@FreeBSD.ORG Subject: Re: FYI: regarding our rfork(2) Message-ID: <199709191848.NAA02645@dyson.iquest.net> In-Reply-To: <199709191604.KAA19167@rocky.mt.sri.com> from Nate Williams at "Sep 19, 97 10:04:17 am"
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Nate Williams said: > John S. Dyson writes: > [ New shared everything call being added ] > > I wrote: > > > it seems that sharing the stack > > > is asking for nothing but trouble. > > John responds: > > > I don't disagree with what you are saying, however, we need to be able > > to have full access to the stacks in every thread. Of course, we would > > be wise to create guard page(s) between stacks. > > Why do we need to have access to the stack? Is it *only* for the thread > 'kernel' that runs in user-land that does the 'context-switching' > between the threads, or will each thread have access to another thread's > stack. I can definitely see the need for the former, but *NOT* the > latter. > Actually, both need it. Otherwise, we will be incompatible with the rest of the world. > > The great strength about Unix is that another 'process' can'tt muck with > another 'processes' easily, and with threads I'd like to see this taken > to whatever extreme as possible given the constraints of implementation. > The threads are a different issue. I don't disagree with the threads stacks being isolated for philosophical reasons -- however it is just wrong from a compatibility standpoint. If we had a type of thread that had isolated stacks, it would be nice, but that is a different exercise. -- John dyson@freebsd.org jdyson@nc.com
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