Hi,

I did provide wrong ptrace data which should fail on their write.
	error (_("Unexpected error setting hardware debug registers"));
But GDB did not print that error, only inferior did hang, because the data was
not written.

It is because this error/exception gets suppressed by:
linux_resume_one_lwp():
1578          if (!check_ptrace_stopped_lwp_gone (lp))
1579            throw_exception (ex);

Which happens because check_ptrace_stopped_lwp_gone()
expects 'T (tracing stop)' while recent Linux kernels
provide 't (tracing stop)' instad.
	What does lowercase t means in ps state code
	http://stackoverflow.com/questions/35895886/what-does-lowercase-t-means-in-ps-state-code

Found it on:
	kernel-4.4.6-301.fc23.aarch64
by:
	gdb/nat/aarch64-linux-hw-point.c
	-  ctrl |= ((1 << len) - 1) << 5;
	+  ctrl |= (((1 << len) - 1)&~1) << 5;

It does not change testsuite results on that F-23.aarch64 machine.
I see no real regessions on rawhide.x86_64 machine (with F-23 kernel) although
there were some fuzzy results I will need to check more.

OK for check-in?


Thanks,
Jan