@Ruhrnalist Das ist der unschlagbare Vorteil der #Digitalisierung bei #DB #bahn. Anstatt den Reisenden tatsächlich aktiv zu unterstützen, reicht der automatisierte Hinweis "bitte prüfen Sie ..." Das Gewährleisten einer zuverlässigen Reisekette wird von der Bring- zur Holschuld.

@700Sachen ja, weil #DB von inkompetenten Managern regiert und #Autzentrismus bei #Verkehrtministern sowas macht!

Of course, my CPU emulator didn't bother to support TF, since it was an edge case and not generally relevant to games. However, this discovery meant that I needed to bite the bullet and add support for tracing.

When the TF is set, the next instruction executes and then afterwards a #DB (debug) fault is generated. This is interpreted by Windows as an EXCEPTION_SINGLE_STEP, which is handled by some fairly sophisticated logic in the SecuROM exception handler.

The basic gist is that once the TF is enabled, the handler continues to re-enable it and trace, instruction-by-instruction, until a special breakpoint instruction turns it off. It also has logic to detect when a #DB instruction happens outside of the protected code (e.g., a system call), and automatically disables tracing by setting a hardware breakpoint on the return address of the function that was called.

This involved a whole lot of work implementing hardware instruction breakpoints and some precise details of the TF behavior in my emulator.

One additional quirk that bit me is that if a hardware instruction breakpoint is set, it generates a #DB exception just like a single step. I originally thought that Windows was smart enough to translate this into an EXCEPTION_BREAKPOINT, but no, it still comes in as an EXCEPTION_SINGLE_STEP.

So after implementing all this, I see that the code extracts several files including cms32_nt.dll, which it then calls LoadLibrary on.

The DllMain funciton of cms32_nt.dll does a bunch of decompression/decryption logic before deliberately writing to offset 0 of the loaded image. On real NT-based system this causes a fault, but in my emulator, I wasn't explicitly protecting this area, so I was missing the fault. This led me to implement logic to mark certain pages as read-only so that I would catch errant writes here.

With that in place, I then landed in the exception handler for the entry point of cms32_nt.dll, which does some interesting things to ensure that it's only been called in the context of a LoadLibrary from a known accomplice....

@sebwilken
Freitags auf der Strecke von Berlin und Hamburg. Der #ICE rumpelt sich bei 105 Minuten Fahrt laut Fahrplan 25 Bonusminuten rein, der Anschluss wartet nicht. Wohl besser als der voraus fahrende Zug: der kam in Berlin schon mit 85 Min. Verspätung an.
Ach ja: Toiletten sehen aus wie Sau, weil der Zug überbesetzt aus München kam.
Vielleicht kein Bashing der #Bahn, aber wieder mal ordentlich Frust über die #DB

Die #DB gehört komplett #verstaatlicht und die #Manager wie #Verkehrtminister die's gegen die Wang gefahren haben, in Regeess genommen!

#DB was late indeed, but I got to Radstadt not too late anyway.

My hotel was close to the station horizontally, but with vertical dimension counted, a tad further.

The main street was like a set from a movie Twin Peaks goes Alpine. No spots, everything in order, mostly decoration related and other money swallowing shops, added with a tattoo parlour just to fool us.

The #IBSIC25 working group meeting went fine, even if we didn't resolve all the problems of #MediaArt #Curating yet. #IBSIC was a very nice experience, meeting new and old friends, talking art, scorning entertainment, you know the drill. Next year again, if I stealthily managed to manipulate another moderator's post for me.

Anyway, #Interrail continues, I'm now on my 3,5 day journey to the next stop Skopje, going to overnight in Radstadt. 13-14 h #TrainTravel, depending on how late #DB will be.