To reproduce the problem, simply:
- Install ReactOS as usually by passing the 1st setup stage, with the settings you want.
- Pass the 2nd setup stage as usually, same with any settings.
- For booting in 3rd stage, select ReactOS (LogFile) mode from boot menu.
- Boot the system.
- After booting into Desktop, open My Computer, go to %SystemRoot% and look at the list of files.
0.4.15-dev-2840-g5c332f6 creates the log successfully, so it exists in the system directory as well.
0.4.15-dev-2841-g608032b - 0.4.15-dev-2843-g54ecf70 are unbootable for me, they fail at initializing devices at 1st setup stage, with bugcheck 0x000000c2 when loading i8042prt.sys. So due to this, I can't test these builds.
0.4.15-dev-2844-g835c302 - is booting successfully again, but the log is not created anymore.
This makes debugging on real hardware without COM cable completely impossible, since there are no any other options to show debug output from user mode, if I have no COM port.
The last good commit is not related to KD, but the first unbootable and the first bad commits had a lot of improvements in Kernel Debugger, so most of all, they caused this problem as well.