Re: [Qemu-devel] [Bug 645662] Re: Python 3.1.2 math errors with Qemu 0.12.5

[Arno Wagner <645662@bugs.launchpad.net>]

I had a brief look at softfloat. In principle, it should fix the 
issue, but only if the FPU uses 80-bit double-extended-precision
internally. I guess the qemu FPU is still stuck at 64 bit double
internally and that does not cut it for some calculations.

Just to be sure, I re-tested the code from comment 1 and it does
work as expected with a real FPU.

Regards,
Arno


On Mon, Jan 23, 2017 at 22:20:18 CET, Thomas Huth wrote:
> Looks like your test code from comment #1 still prints out a wrong
> value, so the bug has apparently not been fixed by the FPU updates...
> 
> ** Changed in: qemu
>        Status: Incomplete => Triaged
> 
> -- 
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/645662
> 
> Title:
>   Python 3.1.2 math errors with Qemu 0.12.5
> 
> Status in QEMU:
>   Triaged
> 
> Bug description:
>   When doing the regression tests for Python 3.1.2 with Qemu 0.12.5, (Linux version 2.6.26-2-686 (Debian 2.6.26-25lenny1)),
>   gcc (Debian 4.3.2-1.1) 4.3.2, Python compiled from sources within qemu,
>   3 math tests fail, apparently because the floating point unit is buggy. Qmeu was compiled from original sources
>   on Debian Lenny with kernel  2.6.34.6 from kernel.org, gcc  (Debian 4.3.2-1.1) 4.3. 
> 
>   Regression testing errors:
> 
>   test_cmath
>   test test_cmath failed -- Traceback (most recent call last):
>     File "/root/tools/python3/Python-3.1.2/Lib/test/test_cmath.py", line 364, in
>       self.fail(error_message)
>   AssertionError: acos0034: acos(complex(-1.0000000000000002, 0.0))
>   Expected: complex(3.141592653589793, -2.1073424255447014e-08)
>   Received: complex(3.141592653589793, -2.1073424338879928e-08)
>   Received value insufficiently close to expected value.
> 
>   
>   test_float
>   test test_float failed -- Traceback (most recent call last):
>     File "/root/tools/python3/Python-3.1.2/Lib/test/test_float.py", line 479, in
>       self.assertEqual(s, repr(float(s)))
>   AssertionError: '8.72293771110361e+25' != '8.722937711103609e+25'
> 
>   
>   test_math
>   test test_math failed -- multiple errors occurred; run in verbose mode for deta
> 
>   =>
> 
>   runtests.sh -v test_math
> 
>   le01:~/tools/python3/Python-3.1.2# ./runtests.sh -v test_math
>   test_math BAD
>    1 BAD
>    0 GOOD
>    0 SKIPPED
>    1 total
>   le01:~/tools/python3/Python-3.1.2#
> 
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/qemu/+bug/645662/+subscriptions

-- 
Arno Wagner,     Dr. sc. techn., Dipl. Inform.,    Email: arno@wagner.name
GnuPG: ID: CB5D9718  FP: 12D6 C03B 1B30 33BB 13CF  B774 E35C 5FA1 CB5D 9718
----
A good decision is based on knowledge and not on numbers. -- Plato

If it's in the news, don't worry about it.  The very definition of 
"news" is "something that hardly ever happens." -- Bruce Schneier

-- 
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https://bugs.launchpad.net/bugs/645662

Title:
  Python 3.1.2 math errors with Qemu 0.12.5

Status in QEMU:
  Triaged

Bug description:
  When doing the regression tests for Python 3.1.2 with Qemu 0.12.5, (Linux version 2.6.26-2-686 (Debian 2.6.26-25lenny1)),
  gcc (Debian 4.3.2-1.1) 4.3.2, Python compiled from sources within qemu,
  3 math tests fail, apparently because the floating point unit is buggy. Qmeu was compiled from original sources
  on Debian Lenny with kernel  2.6.34.6 from kernel.org, gcc  (Debian 4.3.2-1.1) 4.3. 

  Regression testing errors:

  test_cmath
  test test_cmath failed -- Traceback (most recent call last):
    File "/root/tools/python3/Python-3.1.2/Lib/test/test_cmath.py", line 364, in
      self.fail(error_message)
  AssertionError: acos0034: acos(complex(-1.0000000000000002, 0.0))
  Expected: complex(3.141592653589793, -2.1073424255447014e-08)
  Received: complex(3.141592653589793, -2.1073424338879928e-08)
  Received value insufficiently close to expected value.

  
  test_float
  test test_float failed -- Traceback (most recent call last):
    File "/root/tools/python3/Python-3.1.2/Lib/test/test_float.py", line 479, in
      self.assertEqual(s, repr(float(s)))
  AssertionError: '8.72293771110361e+25' != '8.722937711103609e+25'

  
  test_math
  test test_math failed -- multiple errors occurred; run in verbose mode for deta

  =>

  runtests.sh -v test_math

  le01:~/tools/python3/Python-3.1.2# ./runtests.sh -v test_math
  test_math BAD
   1 BAD
   0 GOOD
   0 SKIPPED
   1 total
  le01:~/tools/python3/Python-3.1.2#

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