After adjusting my flash map, I noticed the following error.
This error occurs whenever either of the two slot partitions is assigned more than 4MB. In the case above, it was assigned 6MB.
A comparison of the ´zephyr_pre0.map´ from both compilations shows that sector_buffers requires more DRAM.
As a workaround, I increased ´BOOTLOADER_DRAM_SEG_LEN´ in ´zephyr/soc/espressif/esp32s3/memory.h´ by 0x2000. The error no longer occurs, but I am not sure about the side effects in regards to secure boot and other security features.
The sector_buffers reserve 12 bytes for each sector (4KB of flash) for both arrays. So, <(partition_size / 4000) 12 2> bytes are allocated in .bss.sector_buffers. This explains why the DRAM overflows when the partition size exceeds a certain limit.
Update 2:
At the end it seems that only 16 bytes per sector is used (based on calculations with zephyr_pre0.map)
To fix this, the limit would need to adjusted based on the number of sectors.
To Reproduce
Steps to reproduce the behavior:
build any example project with esp32s3 with --sysbuild
increase any image-slot in partition table to a size > 4MB
See error
Expected behavior
BOOTLOADER_DRAM_SEG_LEN should also consider the maximal sectors and adjust respectively.
Impact
We cannot use our full flash storage for image OTA.
Logs and console output
/usr/local/zephyr-sdk-0.16.8/xtensa-espressif_esp32s3_zephyr-elf/bin/../lib/gcc/xtensa-espressif_esp32s3_zephyr-elf/12.2.0/../../../../xtensa-espressif_esp32s3_zephyr-elf/bin/ld.bfd: zephyr/zephyr_pre0.elf section '.bss' will not fit in region 'dram_seg'
/usr/local/zephyr-sdk-0.16.8/xtensa-espressif_esp32s3_zephyr-elf/bin/../lib/gcc/xtensa-espressif_esp32s3_zephyr-elf/12.2.0/../../../../xtensa-espressif_esp32s3_zephyr-elf/bin/ld.bfd: DRAM segment data does not fit.
/usr/local/zephyr-sdk-0.16.8/xtensa-espressif_esp32s3_zephyr-elf/bin/../lib/gcc/xtensa-espressif_esp32s3_zephyr-elf/12.2.0/../../../../xtensa-espressif_esp32s3_zephyr-elf/bin/ld.bfd: region `dram_seg' overflowed by 7152 bytes
After adjusting my flash map, I noticed the following error.
This error occurs whenever either of the two slot partitions is assigned more than 4MB. In the case above, it was assigned 6MB.
A comparison of the ´zephyr_pre0.map´ from both compilations shows that sector_buffers requires more DRAM.
As a workaround, I increased ´BOOTLOADER_DRAM_SEG_LEN´ in ´zephyr/soc/espressif/esp32s3/memory.h´ by 0x2000. The error no longer occurs, but I am not sure about the side effects in regards to secure boot and other security features.
This issue is originally opened at mcuboot repo: https://github.com/mcu-tools/mcuboot/issues/2094
Update: I've gathered a few more insights:
The sector_buffers reserve 12 bytes for each sector (4KB of flash) for both arrays. So, <(partition_size / 4000) 12 2> bytes are allocated in .bss.sector_buffers. This explains why the DRAM overflows when the partition size exceeds a certain limit.
Update 2: At the end it seems that only 16 bytes per sector is used (based on calculations with zephyr_pre0.map)
To fix this, the limit would need to adjusted based on the number of sectors.
To Reproduce
Steps to reproduce the behavior:
Expected behavior BOOTLOADER_DRAM_SEG_LEN should also consider the maximal sectors and adjust respectively.
Impact
We cannot use our full flash storage for image OTA.
Logs and console output
Environment: