An application using embassy_time and "time-driver-rtc1" from embassy-nrf crashes.

(HOST) INFO  flashing program (8.71 KiB)
(HOST) INFO  success!
────────────────────────────────────────────────────────────────────────────────
────────────────────────────────────────────────────────────────────────────────
stack backtrace:
   0: HardFaultTrampoline
      <exception entry>
   1: _ZN4core3ptr13read_volatile17hd3f8821b78d6920fE
        at /rustc/8b705839cd656d202e920efa8769cbe43a5ee269/library/core/src/ptr/mod.rs:1474:9
   2: _ZN5vcell21VolatileCell$LT$T$GT$3get17h846ed7bb76a64525E
        at /Users/martin/.cargo/registry/src/github.com-1ecc6299db9ec823/vcell-0.1.3/src/lib.rs:33:18
   3: _ZN11nrf9160_pac7generic14Reg$LT$REG$GT$4read17h781ecf172b477ff2E
        at /Users/martin/.cargo/registry/src/github.com-1ecc6299db9ec823/nrf9160-pac-0.11.0/src/generic.rs:65:19
   4: _ZN84_$LT$embassy_nrf..time_driver..RtcDriver$u20$as$u20$embassy_time..driver..Driver$GT$3now17h4e33ced8e698ee26E
        at /Users/martin/.cargo/git/checkouts/embassy-9312dcb0ed774b29/d49d1b6/embassy-nrf/src/time_driver.rs:218:23
   5: _embassy_time_now
        at /Users/martin/.cargo/git/checkouts/embassy-9312dcb0ed774b29/d49d1b6/embassy-time/src/driver.rs:156:13
   6: _ZN12embassy_time6driver3now17hf91ab4d33d5c6c11E
        at /Users/martin/.cargo/git/checkouts/embassy-9312dcb0ed774b29/d49d1b6/embassy-time/src/driver.rs:126:14
   7: _ZN12embassy_time7instant7Instant3now17h0483671508ea8743E
        at /Users/martin/.cargo/git/checkouts/embassy-9312dcb0ed774b29/d49d1b6/embassy-time/src/instant.rs:21:26
   8: _ZN16embassy_executor3raw8Executor4poll17h42b4164cf3414afbE
        at /Users/martin/.cargo/git/checkouts/embassy-9312dcb0ed774b29/d49d1b6/embassy-executor/src/raw/mod.rs:358:42
   9: _ZN16embassy_executor4arch8Executor3run17hb54781054eaf4739E
        at /Users/martin/.cargo/git/checkouts/embassy-9312dcb0ed774b29/d49d1b6/embassy-executor/src/arch/cortex_m.rs:54:17
  10: _ZN7bateman18__cortex_m_rt_main17hf74310984f680484E
        at src/main.rs:12:1
  11: main
        at src/main.rs:12:1
  12: Reset
(HOST) ERROR the program panicked

If I run it without any time features it works.

For now, this yields some linker issues. The produced binary is too large to fit into the FLASH region. Temporarily increasing its size to 100K in order to be able to run cargo size, the linker gives:

[...]
rust-lld: error: undefined symbol: _critical_section_1_0_acquire
[...]
rust-lld: error: undefined symbol: _critical_section_1_0_release
[..]

We use the cortex m bootload function: https://github.com/tweedegolf/dis-bootloader/blob/4741e294239b370745c81ddd9afb08da6a9a7ba3/bootloader/src/main.rs#L371 But that doesn't change the vector table. We should do that.

We're getting:

error: opaque type's hidden type cannot be another opaque type from the same scope
  --> bootloader/src/main.rs:34:1
   |
34 | #[embassy::main]
   | ^^^^^^^^^^^^^^^^ one of the two opaque types used here has to be outside its defining scope
   |
note: opaque type whose hidden type is being assigned
  --> bootloader/src/main.rs:34:1
   |
34 | #[embassy::main]
   | ^^^^^^^^^^^^^^^^
note: opaque type being used as hidden type
  --> bootloader/src/main.rs:34:1
   |
34 | #[embassy::main]
   | ^^^^^^^^^^^^^^^^
   = note: this error originates in the attribute macro `::embassy::task` (in Nightly builds, run with -Z macro-backtrace for more info)

Probably need to update to a newer version of Embassy

Suggestion by Dirbaio:

There's one trick to swap without needing scratch space, just needs slot B to be 1 page bigger.

[ABC] [abc.]
[ABC] [abcC]
[ABc] [abcC]
[ABc] [abBC]
[Abc] [abBC]
[Abc] [aABC]
[abc] [aABC]
[abc] [.ABC]

Needs "moving" each page just once, and each page gets written just once (so if your flash can do 10k erases you can do 10k swaps, with scratch you can do less because you're "concentrating" many erases into the scratch pages). After swap slot B is "shifted" by 1, so you need to do the "unswap" in the reverse order to account for that.