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Date: Fri, 18 Feb 2000 17:50:46 +0900 (JST)
From: Takayuki HOSODA <lyuka@sakura.finetune.co.jp>
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Subject: i386/16802: An user math program have the system on K6-2/III freeze
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>Number:         16802
>Category:       i386
>Synopsis:       An user math program have the system on K6-2/III freeze
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Fri Feb 18 01:00:02 PST 2000
>Closed-Date:
>Last-Modified:
>Originator:     Takayuki HOSODA
>Release:        FreeBSD 3.4-RELEASE i386
>Organization:
Finetune co., ltd.
>Environment:
FreeBSD-3.4-RELEASE
(the kernel was build by gcc-2.7.1 with -O2 -i486 options)
The CPU is K6-2/350 or K6-III/400

>Description:
An user math (FFT) program compliled by gcc-2.95 with 
'-O2 -mpreferred-stack-boundary=2' options often have the
system freeze, which is running on AMD's K6-2 or K6-III processor.
 It won't occur on the system running on the intel pentium processor.
 Also, another user program that making use of a public FFT library
(ftp://ftp.fftw.org/pub/fftw/fftw-2.1.3.tar.gz)
configured with '--enable-i386-hacks' shows the same phenomenon.
 No core dumped, no signal recieved, though the user program compiled,
in this case, by gcc-2.7.1 with -g options was runed within the gdb.

>How-To-Repeat:
Generally, tight and fast floating math program compiled by
gcc-2.95 with -mpreferred-stack-boundary=2 options runned on
K6-2 or K6-III processor often cause the system freeze, however,
the same program won't cause the problem runned on the pentium
processor.
 I can send you the program souces in trouble (4KB).
(It can run on pentium processor without problem)

>Fix:
I have no idea for the permanent fix, however, the followings
maight be help for some case at the user hand.

1. You'd better use gcc-2.7.1 instead of gcc-2.95.
2. Don't use -O3 compile option.
3. Never use -mpreferrd-stack-boundary=2 compile option.

>Release-Note:
>Audit-Trail:
>Unformatted:


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