Re: [Qemu-devel] Running QEMU on FreeBSD

[Antony T Curtis <antony.t.curtis@ntlworld.com>]

On Mon, 2004-05-31 at 01:36, Bartosz Fabianowski wrote:
> I just discovered another problem with your patch.
> 
> Before applying your patch, I was using my own hack that resorted to 
> normal precision doubles for FPU emulation. This resulted in incorrect 
> rounding as could be easily seen when running Windows Update. The total 
> number of megabytes to download was something like 10.99999999999998. 
> Obviously, something had gone wrong with precision and rounding.
> 
> However, after I have applied your patch, which imports from Linux the 
> functions required to use long doubles, the situation got worse. The 
> total number of megabytes to be downloaded by Windows Update is now 
> shown as NaN. I know from previous installs that it should be a 
> moderately sized number, something such as 10 or 20 megabytes. So it's 
> not the rounding of an immensely large number or of a ridiculously small 
> one that is going wrong. There is some other issue surfacing here that 
> makes a perfectly normal-sized floating point number become a NaN.

Replace the rintl() function in target-i386/op.c with the following:

CPU86_LDouble rintl(CPU86_LDouble __x) {
  register CPU86_LDouble __result;
  __asm __volatile__ ("frndint" : "=t" (__result) : "0" (__x));
  return __result;
}


> It's 2:30am here in Europe right now and I won't investigate this 
> further tonight. But if you have time to, maybe you can have a look and 
> see if you can find the source of this problem.
> 
> - Bartosz
> 
> 
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