Date: Sun, 14 Sep 1997 10:16:45 -0700 From: Jason Thorpe <thorpej@nas.nasa.gov> To: dyson@freebsd.org Cc: freebsd-hackers@freebsd.org Subject: Re: What is wrong with this snipet? Message-ID: <199709141716.KAA05915@lestat.nas.nasa.gov>
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On Sun, 14 Sep 1997 10:27:52 -0500 (EST) "John S. Dyson" <toor@dyson.iquest.net> wrote: > userland support. RFMEM supports full address space sharing in FreeBSD, > and it is a bug otherwise (whomever implemented it first.) Yes, I know what it does :-) (As does some similar work I'm doing in NetBSD). I was merely commenting that "full address space sharing" is not what the Real Plan 9 rfork(2) call does with RFMEM. My work on an rfork(2) for NetBSD originally was to support user threads. However, a few thing made me change my mind on that (one of them is signal delivery semantics, another is lack of sane way to give the new thread its own stack). Because of these (and other annoyances), it was decided that rfork(2) wasn't the right way to do this, and I punted on the idea of exporting an rfork(2) system call, especially since RFMEM as Plan 9 works isn't particularly useful for threads, and it seems lame to implement RFMEM differently from Plan 9 and still call it RFMEM :-) Of course, the upshot is that a good chunk of the infrastructure is now in place for a sane set of support-for-user-threads system calls, vfork(2) is REAL vfork(2) again, and it gave me an excuse to rototill a bunch of the signal code and data structures (which you also probably want to do if you're using "struct proc" to represent a user thread, and groups of one or more procs to represent a POSIX process). If you're interested in what I did to NetBSD's signal code (I still have a few things to change, because one of the changes I made incresed signal delivery latency a teensy bit, and I want to gain the time back), then drop me a note privately. Jason R. Thorpe thorpej@nas.nasa.gov NASA Ames Research Center Home: +1 408 866 1912 NAS: M/S 258-6 Work: +1 415 604 0935 Moffett Field, CA 94035 Pager: +1 415 428 6939
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