SIM card related Projects » SIMtrace 2

The simtrace2 firmware appears to have a problem (probably a race condition of some sort, with the USB stack) where it accepts the first USB message sent by simtrace2-list after a reset, but then ignores others. During investigation, it was noticed that when sending two commands in a row from a single instance of simtrace2, the first is ignored, and the second is processed.

So, in https://gerrit.osmocom.org/c/simtrace2/+/26864 a hack was put into `simtrace2-tool` so that it sends a fake, empty, error message, to kick the remote SIM firmware into accepting the second, real message. The strange thing is, that when you send two messages like this, it has the side effect of keeping the processor from getting stuck.

So, something about sending two messages has two effects 1.) it kicks the SIM firmware, if it is stuck, and 2.) prevents the SIM firmware from getting stuck in the first place.