Date: Thu, 04 Mar 2004 09:29:03 +1000 From: Peter Grehan <grehan@freebsd.org> To: Daniel Eischen <eischen@vigrid.com> Cc: freebsd-threads@freebsd.org Subject: Re: User-space context switch and floating-point Message-ID: <40466A3F.5070904@freebsd.org> In-Reply-To: <Pine.GSO.4.10.10403030909510.17237-100000@pcnet5.pcnet.com>
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>> Any opinions ? I noticed the alpha/sparc64 routines don't save FP. > > You don't need to save floating point registers when saving the > context from userland. But why is that any different from having to save non-volatile integer registers ? For instance, on PPC, gp regs 14-31, and also fp regs 14-31, need to be saved by the callee if used since they're non-volatile across function calls. > Look at the i386 thr_getcontext(); it only needs to save the FP > control word. Yes, but I thought the i386 FP calling convention was that all FP registers were volatile across calls, so all were preserved by the callee. later, Peter.home | help
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