Cenk and I put some effort into making 6LoWPAN work without IPv6; except
for when used with the IPv6 header compression of course. This is why
`gnrc_ipv6` is only really *required* by `gnrc_sixlowpan_iphc` now.
With this change the `gnrc_ipv6` dependency is moved from the
`gnrc_sixlowpan` module to the `gnrc_sixlowpan_iphc` module.
Features must be provided by the board if they're actually
available on board. Other features might be provided by the
CPU.
Some grouping is also removed as it is not necessary.
Leverages common flasher (avrdude) and removes unnecessary exports.
Moreover, a reuse of serial.inc.mk is perfomed from the same
atmega_common/Makefile.include
Allows to use avrdude as a flashing tool in any context
(e.g. not dependent on arduino or atmega) though it only
works (AFAIK) on atmega, but I thought it's better to
have it here as we have other flashing tools.
When either `gnrc_sixlowpan_iphc_nhc` or `gnrc_udp` is not compiled
in `_compressible()` never returns `true`. This causes the
`dispatch` snip in `gnrc_sixlowpan_iphc_send()` to be of length 0,
meaning `dispatch->data` is `NULL`, causing possible crashes when
trying to send IPv6 packets over 6LoWPAN without NHC or UDP.
The default macros GPIO_PIN and GPIO_UNDEF do not have to be overridden. The GPIO_PIN macro definition was even wrong for 40 GPIOs without splitting into ports, even if that did not lead to erroneous behavior.
Loosely based on [the original ping] and [netutil]'s ping
New features (compared to old RIOT version):
- non-positional parameters
- Better duplicate detection (addresses #9387)
- Better asynchronous behavior
- Potential for future move to `sock_ip`
- (Optional) DNS-support
- Multithreading-safe (in case shell-command handler gets called
from multiple threads)
[the original ping]: http://ftp.arl.army.mil/~mike/ping.html
[netutil]: https://www.gnu.org/software/inetutils/
When IPv6 is enabled, the MTU is given. So users(*) sending IPv6 packets can
easily figure out what the supported maximum protocol unit is.
However, when IPv6 is disabled and a user wants to send layer 2 frames directly,
no information about the maximum PDU is available using the shell.
When 6LoWPAN is used, a user may be interested in the layer 2 PDU as well in
order to avoid layer 2 fragmentation.
This PR adds the L2-PDU info to the output of the ifconfig shell command, which
is printed regardless of the use of IPv6.
(*): Here "users" refers to human beings interacting with the shell.
Applications can get the maximum PDU of each layer more easily using
gnrc_netapi_get() with NETOPT_MAX_PACKET_SIZE instead of using a shell command.
