Many MCUs contain some Backup or Low Power SRAM that is retained'even
in the deepest sleep modes.
In such sleep modes the MCU is essentually turned off with only the RTC
still running.
It can be woken by a GPIO or a RTC alarm. When this happens, a reset is
triggered and the normal startup routine is invoked.
This adds bss & data section for this memory in the linker script.
This allows for structures to be placed in it e.g.:
e.g.:
static uint8_t persistent_buffer[64] __attribute__((section(".backup.bss")));
static uint32_t persistent_counter __attribute__((section(".backup.data"))) = 1234;
- Since the Vector table must be naturally aligned to the next power
of two of the amount of supported ISR, and the table will be
placed after riotboot_hdr, we must ensure RIOTBOOT_HRD_LEN has the
same alignment.
A second slot is defined with a calculated size, from the
remaining flash after the bootloader and the first slot.
Both slots are defined as equal size, but it can be overriden.
RIOTBOOT_SLOT_LEN is calculated as an hexadecimal value and
handles ROM_LEN defined as kilobytes like '512K'
This enables support for all the cortex-m0+/3/4/7 arch,
so most boards embedding these are potentially supported.
One needs just to ensure that the CPU can be initialised
at least twice.
Co-authored-by: Gaëtan Harter <gaetan.harter@fu-berlin.de>
Allow defining a specific rom length to use for linking the firmware,
_fw_rom_length, instead of the default configuration to use the whole rom from
_rom_offset to the end.
* Add cortexm_common/Makefile.include FW_ROM_SIZE configuration
* Add an assertion that _fw_rom_length still respects _rom_length
Define _rom_offset with a conditional evaluated at execution time to allow
setting it in compilation rules and generate in the same make instance different
elf files with different configurations.
- removed coretx-m[0|3|4]
- moved their content to cortexm_common
- adjusted cortex Makefiles to this new name
- adjusted cortex Makefiles new structure
- fixes to cortexm-common
- Added ARM CMSIS headers to cortexm_common
- thread_exit fixes to cortexm-common
- cortexm-common adjusted documentation
- cortexm_common added eINT dINT defines for now
Benjamin Valentin