Date: Fri, 31 May 2002 21:19:25 -0400 From: Jake Burkholder <jake@locore.ca> To: Julian Elischer <julian@elischer.org> Cc: FreeBSD current users <current@FreeBSD.ORG> Subject: Re: Seeking OK to commit KSE MIII-again Message-ID: <20020531211925.X62759@locore.ca> In-Reply-To: <Pine.BSF.4.21.0205311747320.29361-100000@InterJet.elischer.org>; from julian@elischer.org on Fri, May 31, 2002 at 05:49:59PM -0700 References: <20020531203317.W62759@locore.ca> <Pine.BSF.4.21.0205311747320.29361-100000@InterJet.elischer.org>
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Apparently, On Fri, May 31, 2002 at 05:49:59PM -0700, Julian Elischer said words to the effect of; > interesting but not exactly brief.. :-) > > > On Fri, 31 May 2002, Jake Burkholder wrote: > > > > > The system call stubs in libc are leaf functions; basically just a > > trap instruction followed by a return. They do not touch the stack > > at all, or change the stack pointer. One of the first few instructions > > on entry to the kernel is a save, which rotates the register window > > and logically saves the call-safe registers onto the user stack > > (the outs become the ins, and the kernel gets new ins and locals, > > with the old ones being saved to the user stack once a flush is > > performed or they get spilled out). > > the question is "when does it switch to the kernel stack?" > (and back?) This is not done by the hardware. Its done by the trap code after the save is executed. > > > > > > Here is a reference: http://www.sparc.com/standards/v9.ps.Z > > downloaded... 300+ pages.. hmm. > > > > > > Jake > > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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