fix: ensure stubs for targets are stored in flash to save RAM space

Dzarda7 · Dzarda7 · commit e3572f317e27 · 2025-07-18T00:22:34.000+02:00
Compiled stub was incorrectly placed in RAM, because the arrays with data
were placed in data.__compound_literal section, which is linked to RAM.
This commit adds const qualifier to the arrays, so they are placed in
rodata.__compound_literal section, which is linked to flash.
diff --git a/cmake/gen_stub_sources.py b/cmake/gen_stub_sources.py
@@ -69,12 +69,12 @@ def read_stub_json(json_file):
             {{
                 .addr = {text_start},
                 .size = {text_size},
-                .data = (uint8_t[]){{{text_str}}},
+                .data = (const uint8_t[]){{{text_str}}},
             }},
             {{
                 .addr = {data_start},
                 .size = {data_size},
-                .data = (uint8_t[]){{{data_str}}},
+                .data = (const uint8_t[]){{{data_str}}},
             }},
         }},
     }},
diff --git a/examples/common/example_common.c b/examples/common/example_common.c
@@ -539,7 +539,7 @@ esp_loader_error_t load_ram_binary(const uint8_t *bin)
         }
 
         size_t remain_size = segments[seg].size;
-        uint8_t *data_pos = segments[seg].data;
+        const uint8_t *data_pos = segments[seg].data;
         while (remain_size > 0) {
             size_t data_size = MIN(ESP_RAM_BLOCK, remain_size);
             err = esp_loader_mem_write(data_pos, data_size);
diff --git a/include/esp_loader.h b/include/esp_loader.h
@@ -87,7 +87,7 @@ typedef struct {
 typedef struct {
     uint32_t addr;
     uint32_t size;
-    uint8_t *data;
+    const uint8_t *data;
 } esp_loader_bin_segment_t;
 
 typedef struct {
diff --git a/src/esp_sdio_stubs.c b/src/esp_sdio_stubs.c
diff --git a/src/esp_stubs.c b/src/esp_stubs.c
diff --git a/src/protocol_uart.c b/src/protocol_uart.c
@@ -57,7 +57,7 @@ esp_loader_error_t loader_run_stub(target_chip_t target)
         }
 
         size_t remain_size = stub->segments[seg].size;
-        uint8_t *data_pos = stub->segments[seg].data;
+        const uint8_t *data_pos = stub->segments[seg].data;
         while (remain_size > 0) {
             size_t data_size = MIN(ESP_RAM_BLOCK, remain_size);
             err = esp_loader_mem_write(data_pos, data_size);

Original file line number	Diff line number	Diff line change
`@@ -539,7 +539,7 @@ esp_loader_error_t load_ram_binary(const uint8_t *bin)`
`539`	`539`	`}`
`540`	`540`
`541`	`541`	`size_t remain_size = segments[seg].size;`
`542`		`- uint8_t *data_pos = segments[seg].data;`
	`542`	`+ const uint8_t *data_pos = segments[seg].data;`
`543`	`543`	`while (remain_size > 0) {`
`544`	`544`	`size_t data_size = MIN(ESP_RAM_BLOCK, remain_size);`
`545`	`545`	`err = esp_loader_mem_write(data_pos, data_size);`
Original file line number	Diff line number	Diff line change
`@@ -57,7 +57,7 @@ esp_loader_error_t loader_run_stub(target_chip_t target)`
`57`	`57`	`}`
`58`	`58`
`59`	`59`	`size_t remain_size = stub->segments[seg].size;`
`60`		`- uint8_t *data_pos = stub->segments[seg].data;`
	`60`	`+ const uint8_t *data_pos = stub->segments[seg].data;`
`61`	`61`	`while (remain_size > 0) {`
`62`	`62`	`size_t data_size = MIN(ESP_RAM_BLOCK, remain_size);`
`63`	`63`	`err = esp_loader_mem_write(data_pos, data_size);`