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
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