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Date: Wed, 26 Mar 97 05:59:53 -0500
From: cr@jcmax.com (Cyrus Rahman)
Message-Id: <9703261059.AA21640@corona.jcmax.com>
To: smp@freebsd.org
Subject: APIC_IO and the fpu
Sender: owner-smp@freebsd.org
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>> >It looks to me that the problem with the fpu stuff might be more a 
>> >function of FPU error handling (irq13 vs. IDT trap #16) rather than just 
>> >plain floating point operations...
>> 
>> I agree, and think that someone could find it by examining what goes on
>> in i386/isa/npx.c:mpxintr().
>
>A further thought, its possible that it could be APIC_IO related, could
>someone run this program on both an APIC_IO and non APIC_IO kernel
>to see if it locks both (I don't have an SMP machine anymore)?
>
>> ========================================================================
>> #include <sys/types.h>
>> #include <signal.h>
>> void blech() { exit(3); }
>> main()
>> {
>>       int i32;
>>       double f;
>>       int result = 0;
>>       signal(SIGFPE, blech);
>> 
>>       f = (double) 0x7fffffff;
>>       f = 10 * f;
>>       i32  = (int) f;
>> 
>>       if (i32 != (int) f)
>>               result |= 1;
>>       exit(result);
>> }
>> ========================================================================
>
>--
>Steve Passe     | powered by
>smp@csn.net     |            FreeBSD

The code runs fine with APIC_IO off, but locks the machine up quite nicely
with it on.  I'm not sure what causes the problem yet...

Cyrus