PTP error in gphoto2 running against Linux kernel 2.6.21.3

Answer 1

Build libgphoto with debug symbols (i.e. CFLAGS=$(CFLAGS) -g in makefile), then try to catch the bug in GDB. Looking at the actual code will give much more information on whether it's a kernel or userspace bug than the super-vague error message.

Answer 2

Apparently it is a userspace bug. Building version 2.4.4 of gphoto-suite on the same VM image and then running works well. The good combo seems to be libgphoto2-2.4.2 and libgphoto2_port-0.8.0, along with gphoto2-2.4.2. Maybe the gphoto-devl mailing list will have the answer as to why.