[Gen 3] 256KB application support

[avtolstoy]

Description

Refer to the SDD

NOTE: this PR also enables LTO on all Gen 3 platforms when building system parts.

NOTE: do not use current version of CLI to flash new 256KB binaries over DFU, this will fail

Steps to Test

NOTE: 3.1.0-alpha.1 and 3.1.0-alpha.2 releases available on staging can be used for testing (test/v3.1.0-alpha.1 and test/v3.1.0-alpha.2 are the respective branches). The releases are fully available on staging and appropriate version of DS is also deployed there.

1. Building larger than 128KB applications should be possible with this branch. They should also run just fine
2. 128KB older applications should still work correctly
3. particle serial inspect should correctly report either type of an application (index = 1, 128KB max) (index = 2, 256KB max)
4. Flashing 128KB older app should override the current 256KB app, even if they don't overlap
5. Flashing 256KB app should override (invalidate) the older 128KB app residing on the device even if they don't overlap
6. Bootloader should function correctly with older versions of system-part1 on the device (mainly the bootloader updates through MBR are a concern and application updates)

Example App

N/A

References

• [CH60338]
• There is an appropriate PR in DS repo

---

Completeness

• User is totes amazing for contributing!
• Contributor has signed CLA (Info here)
• Problem and Solution clearly stated
• Run unit/integration/application tests on device
• Added documentation
• Added to CHANGELOG.md after merging (add links to docs and issues)

[XuGuohui]

• They should also run just fine 128KB older applications should still work correctly
• Building larger than 128KB applications should be possible with this branch.

constexpr uint32_t BUF_SIZE = 250 * 1024;
const uint8_t buf[BUF_SIZE] = {};

void setup() {
    for (uint32_t i = 0; i < BUF_SIZE; i++) {
        Serial.printf("%d", buf[i]);
    }
}

• particle serial inspect should correctly report either type of an application (index = 1, 128KB max) (index = 2, 256KB max)
• Flashing 128KB older app should override the current 256KB app, even if they don't overlap
• Flashing 256KB app should override (invalidate) the older 128KB app residing on the device even if they don't overlap
• Bootloader should function correctly with older versions of system-part1 on the device. This may surprise user that the device enters safe mode after downgrading the pre Device OS versions. This is an expected behavior and it would be better to document this somewhere.

Also, after updating the bootloader, system part1 and the 256K user application, their module version isn't bumped. Should we bump the versions in this branch or postpone to when we cut a release?

[sergeuz]

Let's make it clear in this comment that if both user modules are present, the compatibility one will take precedence and be the only user module returned in the modules info.

[avtolstoy]

Added

[sergeuz]

👍

[sergeuz]

Note that verify_module() still checks that the bootloader's destination address is USER_FIRMWARE_IMAGE_LOCATION and not USER_FIRMWARE_IMAGE_LOCATION_COMPAT.

[avtolstoy]

Good catch, thanks!

[avtolstoy]

Double checked bootloader updates. Works fine with system-part out of this branch and older releases as well.