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[Qemu-devel] QEMU x86_64: bug with floats (with test program)
From: |
Ludovic Drolez |
Subject: |
[Qemu-devel] QEMU x86_64: bug with floats (with test program) |
Date: |
Thu, 21 Dec 2006 17:52:22 +0100 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.8) Gecko/20060628 Debian/1.7.8-1sarge7.1 |
Hi !
I've found a bug in Qemu: conversion of floats to strings fails
in some cases. For example, Ganglia (cluster monitoring software), shows
random values and as well as PHP5 programs.
Compile this and link with libapr-1:
======================test.c===============
#include <stdio.h>
#include <math.h>
#include <apr.h>
#include <apr_strings.h>
void main(void)
{
char buf[60];
double d = M_PI;
snprintf(buf, 60, "%f\n", d);
printf(buf);
apr_snprintf(buf, 60, "%f\n", d);
printf(buf);
}
============================================
Under a SLES 10/64 bits, you'll see something like:
3.141593
3.OjuƧ_
I tested with Qemu 0.8.2 and the CVS, and of course, it works on a real
system (a Dell PE1950).
So it's a QEMU bug. Is it triggered by weird code produced by gcc 4.1.0 ? Or a
FPU emulation bug ? Any ideas ?
--
Ludovic DROLEZ Linbox / Free&ALter Soft
http://lrs.linbox.org
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