Hello, I might have found the trigger for the exec hang at boot. The symptoms were that very early during the program loading by ld.so, it would overflow its stack with 0x40, apparently because there were odd things happening with the GOT. One odd thing was that ld.so was getting loaded at 0x0. That's because it is a PIE. Issues that might come up are that pointer 0x0 could then actually be a should-be-valid pointer... I modified gnumach to load PIE binaries at 0x8000000, like our exec server does, and couldn't reproduce the exec hang at boot. This is now in debian as gnumach version 2:1.8+git20201007-1.
Samuel
