On Linux (and in most of posix-like systems) the baudrate set in struct
termios via cfset[io]speed is actually the index of the standard
baudrates, it's not the baudrate per se (hence the use of B* macros).
On Linux it's possible to set the baudrate by passing the baudrate
itself to TCSETS2 ioctl. Unfortunately it's not possible to include
asm/termbits.h and termios.h in the same compilation unit, so we need to
split it. Here we split into a Linux and a NuttX implementation.
Checking the time on the tcpdump capture, it matches the first fields
from the data:
$ tshark -n -c 4 -r ~/tmp/solo/rc.pcap
1 0.000000 10.1.1.1 → 10.1.1.10 UDP 68 5005 → 5005 Len=26
2 0.019976 10.1.1.1 → 10.1.1.10 UDP 68 5005 → 5005 Len=26
3 0.040046 10.1.1.1 → 10.1.1.10 UDP 68 5005 → 5005 Len=26
4 0.059961 10.1.1.1 → 10.1.1.10 UDP 68 5005 → 5005 Len=26
From the previous commit (first 2 packets):
5fa8 f441 3414 0500 73d7 dc05 dc05 dc05 db05 e803 e803 e803 f401
73f6 f441 3414 0500 74d7 dc05 dc05 dc05 db05 e803 e803 e803 f401
0x0005143441f45fa8 - 0x0005143441f4f673 = 0x4E14 = 19988 (usec)
Which seems to approximately match for the other packets as well. We are
not using the field since we rather get the time when we receive it, but
at least use a better name.