[Qemu-devel] [Bug 1574246] [NEW] Drunken keyboard in go32v2 programs

[felix]

Public bug reported:

QEMU 2.5.0, SeaBIOS 1.9.1; I've been noticing this bug for quite a
while, though.

Steps to reproduce:

# Create a VM image, install DOS in it (doesn't matter which) and launch it.
# Launch a "bare DOS" DPMI host (not an operating system) in it; I tested with 
CWSDPMI and HDPMI32.
# Run a go32v2 program which reads keyboard input (say, the Lua interpreter: 
<http://www.ibiblio.org/pub/micro/pc-stuff/freedos/files/distributions/1.1/repos/devel/lua.zip>;
 the Free Pascal IDE will also do; on the other hand, DOS/4GW programs seem 
unaffected).
# Quickly type in something random (e.g. alternate between hitting "p" and 
"q"), then optionally move the cursor left and right.
# Observe how some keystrokes are missed, and some are caught twice.

The issue does NOT arise:
* on bare metal DOS,
* in VirtualBox,
* in Bochs with stock Plex86 BIOS,
* in Bochs with SeaBIOS,
* in DOSEMU,
* in DOSBox,
* in QEMU when the DPMI host is Windows 3.11/9x
so at this point I'm reasonably sure that it's the fault of either QEMU or 
SeaBIOS, and probably the former. The issue arises regardless of whether KVM is 
enabled.

** Affects: qemu
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1574246

Title:
  Drunken keyboard in go32v2 programs

Status in QEMU:
  New

Bug description:
  QEMU 2.5.0, SeaBIOS 1.9.1; I've been noticing this bug for quite a
  while, though.

  Steps to reproduce:

  # Create a VM image, install DOS in it (doesn't matter which) and launch it.
  # Launch a "bare DOS" DPMI host (not an operating system) in it; I tested 
with CWSDPMI and HDPMI32.
  # Run a go32v2 program which reads keyboard input (say, the Lua interpreter: 
<http://www.ibiblio.org/pub/micro/pc-stuff/freedos/files/distributions/1.1/repos/devel/lua.zip>;
 the Free Pascal IDE will also do; on the other hand, DOS/4GW programs seem 
unaffected).
  # Quickly type in something random (e.g. alternate between hitting "p" and 
"q"), then optionally move the cursor left and right.
  # Observe how some keystrokes are missed, and some are caught twice.

  The issue does NOT arise:
  * on bare metal DOS,
  * in VirtualBox,
  * in Bochs with stock Plex86 BIOS,
  * in Bochs with SeaBIOS,
  * in DOSEMU,
  * in DOSBox,
  * in QEMU when the DPMI host is Windows 3.11/9x
  so at this point I'm reasonably sure that it's the fault of either QEMU or 
SeaBIOS, and probably the former. The issue arises regardless of whether KVM is 
enabled.

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