If `SPI_CS_UNDEF` is given as the `cs` parameter, CS pin must not be handled by the driver. Furthermore, if `cont` parameter is true, CS pin must not be disabled at the end of one transfer.
Thin archives also cause a boot loop when using the flash module.
To prevent further surprises, disable thin archives unconditionally
until the cause for this behaviour is known.
For a yet unknown reason, both esp8266 and esp32 get stuck in a
reboot loop when thin archives are used.
As a workaround, disable thin archives for now if esp_wifi is used.
fixes#12258
* CPU files should already have 'CPU' defined by the board.
* Do not conditionally define CPU as it is not needed.
This is part of cleanup prior to moving the CPU/CPU_MODEL to
Makefile.features.
Instead of having a send buffer as member `esp_wifi` netdev, a local variable is used now as send buffer. This avoids the need for a locking mechanism and reduces the risk of deadlocks.
Receive call back function `_esp_wifi_rx_cb` is called from WiFi hardware driver with a pointer to a frame buffer that is allocated in the WiFi hardware driver. This frame buffer was freed immediately after copying its content to a single local receive buffer of the `esp_wifi` netdev. The local receive buffer remained occupied until the protocol stack had processed it. Further incoming packets were dropped. However, very often a number of subsequent WiFi frames are received at the same time before the first one is processed completely. Having the single local receive buffer to hold only one received frame, led to a number of lost packets, even at low network load. Therefore, a ringbuffer of rx_buf elements was introduced which doesn't store the frames directly but only references to the frame buffers allocated in WiFi hardware driver. Since there is enough memory to hold several frames, the frames buffers allocated in WiFi hardware driver aren't freed immediatly any longer but are kept until the frame is processed by the protocol stack. This results in a much less loss rate of packets.
Events of different type can be pending at the same time. Therefore it is not possible to use ascending identifiers for the presence of a pending event. Rather, each event type has to be represented by one bit. Thes bits ORed identify all types of pending events. In the esp_wifi_isr function all pending events are then handled in one call. Otherwise, some events might be lost.
Use the -gz option to compress ELF sections containing DWARF information.
This saves around 50% of disk space, without any side effects.
See https://gcc.gnu.org/onlinedocs/gcc-9.2.0/gcc/Debugging-Options.html#Debugging-Options
for more infomation on this option.
Some platforms have an outdated toolchain that does not support -gz so
the flag is blacklisted there. Even then, the results are quite impressive.
I used @cladmi's `buildtest` branch (https://github.com/cladmi/RIOT/tree/wip/du/buildtest)
with this change and compiled the `examples/default` application:
```
$ BUILD_IN_DOCKER=1 DOCKER="sudo docker" make -C examples/default buildtest-indocker
```
The size was obtained with:
```
$ find output -name "*.bin.bindirsize" -type f -exec tail -n1 '{}' \; | cut -f 1 | awk '{s+=$1} END {printf "%.0f", s}'
```
Results:
- Vanilla: 10328112 KB (~10GB).
- with -gz: 4982788 KB (~5GB).
This was inspired by #8496.
