[Qemu-devel] [Bug 1248376] [NEW] "fstenv" gets the wrong result in qemu 1.6.1

[Minghua Wang]

Public bug reported:

The float instruction "fstenv" gets the wrong result, when I tested it
in QEMU 1.6.1.

The detailed testing environments are: 
1)the QEMU's guest OS is 32-bit windows 7 professional.(version: 6.1.7600). 
2)the QEMU's host machine I used is 64-bit Fedora Core 13.


I used the following command line to compile QEMU 1.6.1:
./configure --target-list=i386-softmmu
make 
make install

Then, I launched the QEMU guest with the following command:
qemu-system-i386  xxx.img  -m  1024M


Here are some more details:
03FA0005     DAC7                               fcmovb st,st(7)
03FA0007     D97424 F4                     fstenv (28-byte) ptr ss:[esp-0xC]
03FA000B     5B                                    pop ebx
03FA000C     33C9                               xor ecx,ecx

when 0x03FA000B: pop ebx finished excuting,  the value of ebx should be
0x03FA0005. But in QEMU 1.6.1+windows 7 pro(32 bit) which was described
above, ebx's wrongly turned out to be 0x0!

** Affects: qemu
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1248376

Title:
  "fstenv" gets the wrong result in qemu 1.6.1

Status in QEMU:
  New

Bug description:
  The float instruction "fstenv" gets the wrong result, when I tested it
  in QEMU 1.6.1.

  The detailed testing environments are: 
  1)the QEMU's guest OS is 32-bit windows 7 professional.(version: 6.1.7600). 
  2)the QEMU's host machine I used is 64-bit Fedora Core 13.

  
  I used the following command line to compile QEMU 1.6.1:
  ./configure --target-list=i386-softmmu
  make 
  make install

  Then, I launched the QEMU guest with the following command:
  qemu-system-i386  xxx.img  -m  1024M


  Here are some more details:
  03FA0005     DAC7                               fcmovb st,st(7)
  03FA0007     D97424 F4                     fstenv (28-byte) ptr ss:[esp-0xC]
  03FA000B     5B                                    pop ebx
  03FA000C     33C9                               xor ecx,ecx

  when 0x03FA000B: pop ebx finished excuting,  the value of ebx should
  be 0x03FA0005. But in QEMU 1.6.1+windows 7 pro(32 bit) which was
  described above, ebx's wrongly turned out to be 0x0!

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