Implement application description for ESP-IDF image format

[SergioGasquez]

New versions of ESP-IDF bootloader expect to have application description, see https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/system/app_image_format.html#application-description.

Here's the macro in esp-idf-sys: https://github.com/esp-rs/esp-idf-sys/blob/master/src/app_desc.rs#L2

@bugadani suggested having a similar macro on esp_hal::init that could be configured with esp-config

[MabezDev]

One thing we need to be careful about using esp-config is that we namespace those options properly so they're specific to esp-idf's bootloader and won't overlap with any relevant mcu boot options.

[MabezDev]

and we should also be careful to only include the relevant linker changes (e.g https://github.com/espressif/esp-idf/blob/c5865270b50529cd32353f588d8a917d89f3dba4/components/esp_system/ld/esp32/sections.ld.in#L300-L322) when supporting the esp-idf bootloader.

[MabezDev]

Adding the 1.0 blocker as we need to solve this update the bootloaders in espflash for v4? Correct me if I'm wrong

[ivmarkov]

Adding the 1.0 blocker as we need to solve this update the bootloaders in espflash for v4? Correct me if I'm wrong

That's correct. To my understanding, the first bootloaders that do read esp_app_desc_t are the ones from 5.2.3 and 5.3.2. They are specifically reading the two new fields in esp_app_desc_t (which were pulled from the reserved space) and which are named:

• min_efuse_blk_rev_full
• max_efuse_blk_rev_full

They should be set to whatever MCU version range the app can deal with (or to 0 - 99 by default, if the app is compatible with all MCU versions)

[ivmarkov]

There's also this new guy named mmu_page_size which appears in ESP-IDF bootloaders >= 5.4. I haven't looked into it yet.

[ivmarkov]

Related: esp-rs/espflash#741