Subject: Powerpc signal handler with floating point registers
To: None <>
From: chris zhang <>
List: port-powerpc
Date: 02/25/2005 10:32:34
I'm using NetBSD 2.0-RC4 on a powerpc 603 processor
which has the hardware floating point component
enabled. I ran into a situation where it seems the
powerpc floating point registers are not
saved/restored properly by the signal handler. 

The following testing program has a floating computing
loop inside "main" routine. It also sets up a SIGALRM
handler to perform another floating point calculation
periodically. When it runs, I got a lot of error
message from the "fprintf" below, which means the
signal handler probably interferes with the main
program and does not restore the floating point
registers when it returns.

Any idea why this could happen? I tested on i386 ports
and didn't find the same problem, so I guess the
problem is architecture specific.


#include <stdio.h>
#include <signal.h>
#include <sys/time.h>

int alarms;

void testB_alrm_handler(int sig)
 	static double x = 1.2;
 	x = x*x;

int main(void)
 	register double new = 0;
 	register double old = new;
	struct itimerval it;

 	signal(SIGALRM, testB_alrm_handler);

 	it.it_value.tv_sec = 0;
 	it.it_value.tv_usec = 20000;
 	it.it_interval = it.it_value;
 	setitimer(ITIMER_REAL, &it, NULL);

 	for (;;) {
 		new = new + 1;
 		if (new != old + 1)
 			fprintf(stderr, "ERROR. alarms=%d %g != %g\n",
alarms, new, old);
 		old = new;

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