[vbox-dev] Problem in 8042

Felix Kaiser confused at theanykey.de
Sat Sep 13 10:02:23 PDT 2008


8042 hardware implementations provide the value at data port 0x60 after 
read for a small time, so if the port is read again within that time, 
the read value will be the same. The 8042 emulation provided by 
VirtualBox clears that value too fast, seems to be cleared immediately 
after read. Chained 8042 interrupt handlers (keyboard 1, mouse 12) may 
read different values within one interrupt shot resulting in problems 
especially with extended keys and handling key releases. Chained 8042 
handlers are commonly used by DOS applications for handling special keys 
and providing hot keys. Having both PS/2 mouse and keyboard may also 
result in handling mouse data in the keyboard interrupt. The problem 
could be solved by providing the value at the data port unless receiving 
EOI if interrupts are enabled.

At moment many DOS applications doesn't work correctly.

Please let me know if you want to know something more.

Best regards
Felix Kaiser

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