Hi,

I found that the serial remote protocol runs into a deadlock when the serial line is noisy. Below a gdb log fragment with original code:

r +$S05#b8
w +$g#67
r <Timeout: 3 seconds>
w $g#67
r <Timeout: 3 seconds>
w $g#67
r <Timeout: 3 seconds>
w $g#67
r <Timeout: 3 seconds><Timeout: 3 seconds>
w -
r <Timeout: 3 seconds>
w -
r <Timeout: 3 seconds>
w -+

infinitely. Because the target side NetBSD kernel throws all characters until get a new packet start ('$') char.

The patch separates "acknowledge timeout" and "packet retry" cases.
After patching the GDB behaviour changed. The log below generated by patched GDB:

r +$S05#b8
w +$g#67
r <Timeout: 3 seconds><Timeout: 3 seconds><Timeout: 3 seconds>
w $g#67
r <Timeout: 3 seconds><Timeout: 3 seconds><Timeout: 3 seconds>
w $g#67
r

and so on. GDB stay good state after in/out packet loss.

I tried on the GDB 6.5 version under SuSE 10.2 distribution.

Thank you your work,
Zoltán Filyó
zoltan dot filyo at ericsson dot com