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386SWAT debugger (Developers)

posted by mceric, Germany, 28.03.2024, 00:50

> The 386SWAT debugger seems to be able to continue tracing a real-mode (not
> V86) program that goes into protected mode, but I don't quite understand
> how to configure 386SWAT with 67h INTs, and I can't find any assembly
> language examples.
Looking at https://sudleyplace.com/swat/swatdoc.html

here are some thoughts:

http://www.sudleyplace.com/swat/swatinv.html

you can invoke 386swat with ctrl-alt-pad5 while it is waiting in the background, or run to-be-debugged apps via SWATRUN.

http://www.sudleyplace.com/swat/swatmon.html

you can tell 386swat to trigger when an expression becomes true, but this will make everything slow while 386swat looks out for the trigger. You can do stuff like

gm [.csip == 67cd && ax == somevalue

to trigger when the upcoming instruction is INT 67 while AX has a value of your choice.

http://www.sudleyplace.com/swat/swatpro.html

you can tell 386swat to trigger on a subset of things triggering GPF, which includes (if you are in vm86 while emm386 is active) things like interrupts, interrupt flag changing things and I/O port access to watched ports. Usually, emm386 will not watch ports, but things like a virtual sound blaster or emm386 assisting a virtual soundblaster will watch ports.

You can also tell 386swat to trigger on various protected mode faults, interrupts and exceptions with trap... options and you can use vmsint and vmscount to trigger on switches to protected mode via VCPI.

Maybe one of those ideas gets you on the right track, I have not tested them myself.

---
FreeDOS / DOSEMU2 / ...

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