Fix Risc-V alignment & stack issues

Author: will-v-pi

pico_w/wifi/ota_update/CMakeLists.txt

@@ -49,7 +49,7 @@ pico_use_wifi_firmware_partition(picow_ota_update_poll)
 
 pico_hash_binary(picow_ota_update_poll)
 pico_sign_binary(picow_ota_update_poll ${CMAKE_CURRENT_LIST_DIR}/private.pem)
-# pico_set_binary_type(picow_ota_update_background no_flash)
-# pico_package_uf2_output(picow_ota_update_background 0x10000000)
+# pico_set_binary_type(picow_ota_update_poll no_flash)
+# pico_package_uf2_output(picow_ota_update_poll 0x10000000)
 
 pico_add_extra_outputs(picow_ota_update_poll)

pico_w/wifi/ota_update/picow_ota_update.c

@@ -30,8 +30,8 @@ typedef struct TCP_UPDATE_SERVER_T_ {
     struct tcp_pcb *server_pcb;
     struct tcp_pcb *client_pcb;
     bool complete;
-    uint8_t buffer_sent[SHA256_RESULT_BYTES];
-    uint8_t buffer_recv[BUF_SIZE];
+    __attribute__((aligned(4))) uint8_t buffer_sent[SHA256_RESULT_BYTES];
+    __attribute__((aligned(4))) uint8_t buffer_recv[BUF_SIZE];
     int sent_len;
     int recv_len;
     int num_blocks;
@@ -300,6 +300,15 @@ static bool tcp_update_server_open(void *arg) {
 int main() {
     stdio_init_all();
 
+#ifdef __riscv
+    // Increased bootrom stack is required for some of the functions in this example
+    bootrom_stack_t stack = {
+        .base = malloc(0x400),
+        .size = 0x400
+    };
+    rom_set_bootrom_stack(&stack);
+#endif
+
     if (cyw43_arch_init()) {
         printf("failed to initialise\n");
         return 1;