Date: Mon, 07 Jan 2002 21:56:28 -0500 From: Dan Eischen <eischen@vigrid.com> To: arch@freebsd.org Subject: Getcontext resolution? Message-ID: <3C3A5FDC.23866673@vigrid.com>
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I'm incorporating Doug Rabson's comments. makecontext will allow passing pointers as arguments to the start function, and the argument count will not be passed as a parameter: void func_1(int a, ucontext_t *ucp, b) { /* a = 10, b = 20 */ } ... makecontext(ucp, func_1, 4, 10, ucp, 20); I'll also enable full save of the FP state in getcontext(). The optimized code will be commented out (i386 version): /* * XXX - Do we really need to save floating point registers? * * This is an explicit call to get the current context, so * shouldn't the caller be done with the floating point registers? * Contexts formed by involuntary switches, such as signal delivery, * should have floating point registers saved by the kernel. * * As of this writing, the kernel doesn't yet save the FPU state * on signal delivery, so a setcontext on the interrupted context * may yield incorrect results regardless. */ #if 0 fnstcw MC_FP_CW_OFFSET(%edx) /* save control word */ movl $UC_MC_VALID, MC_FLAGS_OFFSET(%edx) /* mcontext valid, no FP */ #else fnsave MC_FP_REGS_OFFSET(%edx) /* save FP regs */ movl $MC_FP_VALID, MC_FLAGS_OFFSET(%edx) /* mcontext and FP valid */ #endif We can enable the optimized code some time later. Is that OK with everyone? -- Dan Eischen To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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