From owner-freebsd-stable  Sun Feb 21  2:37:22 1999
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From: Robert Nordier <rnordier@nordier.com>
Message-Id: <199902211030.MAA01082@ceia.nordier.com>
Subject: Re: MATH_EMULATE on 486SX
In-Reply-To: <Pine.GSO.4.10.9902202341040.21534-100000@tricord.system.pl> from Marcin Cieslak at "Feb 20, 99 11:42:29 pm"
To: saper@system.pl (Marcin Cieslak)
Date: Sun, 21 Feb 1999 12:30:11 +0200 (SAT)
Cc: stable@FreeBSD.ORG
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Marcin Cieslak wrote:
 
> I have reproduced the behaviour described in 
> <3693366C.12CBFA8E@ktinet.com.tw> (on
> freebsd-questions) on 3.0-RELEASE.
> 
> The MATH_EMULATE option is present (without it
>  the kernel panics right after npx0) and we get:
> 
> npx0 on motherboard
> npx0: 387 emulator
> changing root device ...
> 
> and so on.
> 
> The system boots, but fsck, ping, X server and
> some other tools abort at some point with signal 10.
> However, one can log in and spawn a shell.
> 
> A quick backtrack on fsck compiled with -g
> shows that it core dumps on the line (main.c:271):
> 
>    printf("(%d frags, %d blocks, %.1f%% fragmentation)\n",
> 
> And the last output from fsck was:
> 
> /dev/rwd0s1e: 5355 files, 89173 used, 64610 free 
> 
> It segfaults on printf("%f") -- so the error is in the
> floating point code, presumably in FP emulation.
> 
> The same configuration (I am just removing hdd) works
> on 486DX fine.

This sounds like the problem fixed by the following commit:

| rnordier    1998/10/21 10:10:49 PDT
| 
|   Modified files:
|     sys/i386/i386        math_emulate.c 
|   Log:
|   Get things limping along again for the 80386 and friends.  The
|   ELF assembler emits a redundant operand-size prefix for the
|   fnstsw %ax instruction, and this stops the show for 3.0-RELEASE.
|   
|   Revision  Changes    Path
|   1.30      +5 -2      src/sys/i386/i386/math_emulate.c

-- 
Robert Nordier


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