Enhancements for the esp32_flash task #52

UncleGrumpy · 2025-07-28T04:25:31Z

Changes include automatic detection of the beam application partition (default main.avm) to prevent overwriting the wrong flash sectors. This prevents overwriting Elixir library modules for Elixir supported builds, and assures that the application will be written to the same address that AtomVM will load and run. When flashing to a device with a custom partition table the app_partition parameter should be supplied if the app partition is not named main.avm.

Other changes include:

Device port is now auto discovered instead of hard coded
Improved error reporting
Stacktraces are only displayed in diagnostic mode
Dialyzer warnings for atomvm_rebar3_plugin esp32_flash provider fixed

pguyot

(Partial review)

src/atomvm_esp32_flash_provider.erl

pguyot · 2025-12-08T07:55:17Z

src/atomvm_esp32_flash_provider.erl

+            auto ->
+                read_flash_offset(EspTool, Port, Partition, State);
+            Val ->
+                Offset0 = read_flash_offset(EspTool, Port, Partition, State),


Nicer transition behaviour would be to check that offset matches the beginning of any partition (main.avm or named otherwise).

Good idea! Now if the given offset does not match the expected partition name a warning will be issued, but as long as it is a data partition of a valid subtype (any subtype not specifically reserved for other purposes - i.e. cordump, nvs, nsv_keys, fat, etc) the partition will be used.

src/esp_part_dump.erl

pguyot · 2025-12-08T08:04:33Z

src/esp_part_dump.erl

+        "0xc00",
+        TempFile
+    ]),
+    os:cmd(Cmd),


os:cmd doesn't return the status. We may want to use the good old open_port({spawn_executable, Esptool}).

I updated this file and the esp32_flash provider to use open_port/2, this had the added benefit of faster flash operations and quieter output.

src/esp_part_dump.erl

Changes error reporting for the esp32_flash task to include stack trace when rebar3 is executed with DIAGNOSTIC=1 or DEBUG=1. Signed-off-by: Winford <winford@object.stream>

The `offset` for the beam application partition is now read from the partition table on the attached esp32 device. When a custom partition table is used that does not use `main.avm` for the beam app partition name the `app_partition` parameter should be used to specify the application partition to be flashed. Valid application partition sub-types (the type is `data`) are `phy` or `0xAA`. If the `offset` parameter is specified it will be used to verify that the offset address of the application partition matched the expected value. This may be used to prevent flashing to a standard build of AtomMV for application that require a custom partition table. The `port` that the ESP32 is attached to is now auto discovered by default. When more than one ESP32 device is plugged into USB the port should be specified to control which device is flashed. Error reporting has been improved with descriptive error messages. Dialyzer warnings for the esp32_flash task have been fixed when analyzing atomvm_rebar3_plugin. Signed-off-by: Winford <winford@object.stream>

pguyot · 2025-12-17T07:22:25Z

src/atomvm_esp32_flash_provider.erl

-    I.
+-spec integer_from_string(S :: list() | integer()) -> Value :: integer().
+integer_from_string("auto") ->
+    -1;


Maybe we should have this function return integer() | auto instead of using -1 as a magic number.

pguyot · 2025-12-17T07:23:09Z

src/atomvm_esp32_flash_provider.erl

+    TempFile = get_part_tempfile(State),
+    Address =
+        case Offset of
+            -1 ->


We probably want auto here.

pguyot · 2025-12-17T07:24:12Z

src/atomvm_esp32_flash_provider.erl

+                        rebar_api:abort("Partition ~s not found!", [Partition]);
+                    error:invalid_partition_table ->
+                        rebar_api:abort(
+                            "Error parsing partition table, possible line noise reading from device.",


Port already open with minicom is more likely here than line noise ;-)

pguyot · 2025-12-17T07:25:08Z

src/atomvm_esp32_flash_provider.erl

+                end;
+            Val ->
+                Offset0 = read_flash_offset(EspTool, Port, Partition, TempFile),
+                case Val =:= Offset0 of


case Offset0 of or if Val =:= Offset0 look more Erlang to me.

pguyot · 2025-12-17T07:26:43Z

src/atomvm_esp32_flash_provider.erl

        end,
-    Cmd = lists:join(" ", [
-        EspTool,
+    [ProjectAppAVM | _] = [get_avm_file(ProjectApp) || ProjectApp <- ProjectApps],


Are you using side effects from get_avm_file/1 here or could you just process the first ProjectApps (with hd(ProjectApps))?

pguyot · 2025-12-17T07:48:17Z

test/driver/scripts/esptool.sh

+while [ "${#}" -gt 0 ]; do
+    case ${1} in
+        read_flash ) shift
+            if [ "${1}" = "0x8000" ] && [ "${2}" = "0xC00" ] || [ "${2}" = "0xc00" ]; then


Suggested change

if [ "${1}" = "0x8000" ] && [ "${2}" = "0xC00" ] || [ "${2}" = "0xc00" ]; then

if [ "${1}" = "0x8000" ] && { [ "${2}" = "0xC00" ] || [ "${2}" = "0xc00" ]; }; then

pguyot · 2025-12-17T07:51:11Z

src/atomvm_esp32_flash_provider.erl

+    I;
+integer_from_string(S) when is_list(S) ->
+    S0 = string:trim(S),
+    case lists:prefix("0x", S0) of


You should use string:prefix/2 or lists:sublist(S0, 2) instead of lists:subtract(S0, "0x")

pguyot · 2025-12-17T07:55:47Z

src/esp_part_dump.erl

+
+-spec lookup_partition_by_name(Name :: string(), Partitions :: binary()) ->
+    Offset :: non_neg_integer().
+lookup_partition_by_name(Name, Partitions) ->


lookup_partition_by_name/2 and lookup_partition_by_offset should have the same signature (return error tuple or raise).

pguyot · 2025-12-17T07:59:48Z

src/atomvm_esp32_flash_provider.erl

+
+%% @private
+get_part_tempfile(State) ->
+    OutDir = filename:absname(rebar_dir:base_dir(State)),


We probably should call mktemp(1) here

pguyot · 2025-12-17T08:01:21Z

src/esp_part_dump.erl

+        {Tool, {exit_status, Status}} ->
+            error({"esptool.py failure", Status})
+    after 120000 ->
+        error("esptool.py failed (2 minute timeout exceeded)")


Tool is not closed here.

UncleGrumpy marked this pull request as draft July 29, 2025 02:22

UncleGrumpy force-pushed the detect_esp32_offset branch 3 times, most recently from 5685f2a to 91a5fc9 Compare August 2, 2025 05:59

UncleGrumpy marked this pull request as ready for review August 2, 2025 06:00

UncleGrumpy force-pushed the detect_esp32_offset branch from 91a5fc9 to 783d3ad Compare August 2, 2025 08:14

UncleGrumpy requested review from bettio and pguyot October 21, 2025 14:12

UncleGrumpy force-pushed the detect_esp32_offset branch 2 times, most recently from 586a1ef to d334c12 Compare December 8, 2025 07:35

UncleGrumpy requested review from pguyot and removed request for bettio and pguyot December 8, 2025 07:36

pguyot reviewed Dec 8, 2025

View reviewed changes

Make esp32_flash include stack trace in diagnostic mode

e62d9dd

Changes error reporting for the esp32_flash task to include stack trace when rebar3 is executed with DIAGNOSTIC=1 or DEBUG=1. Signed-off-by: Winford <winford@object.stream>

UncleGrumpy force-pushed the detect_esp32_offset branch 2 times, most recently from 3a391b9 to 4d4e57e Compare December 16, 2025 03:25

UncleGrumpy requested a review from pguyot December 16, 2025 03:44

UncleGrumpy force-pushed the detect_esp32_offset branch 2 times, most recently from 11dfd1c to 9b7d519 Compare December 16, 2025 06:04

UncleGrumpy force-pushed the detect_esp32_offset branch from 9b7d519 to fe79208 Compare December 16, 2025 06:20

pguyot reviewed Dec 17, 2025

View reviewed changes

	if [ "${1}" = "0x8000" ] && [ "${2}" = "0xC00" ] \|\| [ "${2}" = "0xc00" ]; then
	if [ "${1}" = "0x8000" ] && { [ "${2}" = "0xC00" ] \|\| [ "${2}" = "0xc00" ]; }; then

Enhancements for the esp32_flash task #52

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Enhancements for the esp32_flash task #52

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UncleGrumpy commented Jul 28, 2025

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