refactor(core): allow running coreapp emulator as an applet

diff --git a/core/embed/projects/kernel/main.c b/core/embed/projects/kernel/main.c
index 4d48eb4d3..b6aafe78e 100644
--- a/core/embed/projects/kernel/main.c
+++ b/core/embed/projects/kernel/main.c
@@ -223,10 +223,9 @@ static void kernel_loop(applet_t *coreapp) {
 static void show_rsod(const systask_postmortem_t *pminfo) {
 #ifdef RSOD_IN_COREAPP
   applet_t coreapp;
-  coreapp_init(&coreapp);
 
   // Reset and run the coreapp in RSOD mode
-  if (coreapp_reset(&coreapp, 1, pminfo, sizeof(systask_postmortem_t))) {
+  if (coreapp_init(&coreapp, 1, pminfo, sizeof(systask_postmortem_t))) {
     // Run the applet & wait for it to finish
     applet_run(&coreapp);
     // Loop until the coreapp is terminated
@@ -286,10 +285,9 @@ int main(void) {
 
   // Initialize coreapp task
   applet_t coreapp;
-  coreapp_init(&coreapp);
 
   // Reset and run the coreapp
-  if (!coreapp_reset(&coreapp, 0, NULL, 0)) {
+  if (!coreapp_init(&coreapp, 0, NULL, 0)) {
     error_shutdown("Cannot start coreapp");
   }
 
diff --git a/core/embed/sys/task/inc/sys/applet.h b/core/embed/sys/task/inc/sys/applet.h
index 71acfc4b2..8188dc933 100644
--- a/core/embed/sys/task/inc/sys/applet.h
+++ b/core/embed/sys/task/inc/sys/applet.h
@@ -36,10 +36,8 @@ typedef struct {
   applet_layout_t layout;
   // Applet privileges
   applet_privileges_t privileges;
-
   // Applet task
   systask_t task;
-
 } applet_t;
 
 // Initializes the applet structure
diff --git a/core/embed/sys/task/inc/sys/coreapp.h b/core/embed/sys/task/inc/sys/coreapp.h
index bb550a5a9..492ddf105 100644
--- a/core/embed/sys/task/inc/sys/coreapp.h
+++ b/core/embed/sys/task/inc/sys/coreapp.h
@@ -45,20 +45,31 @@ typedef struct {
   void* saes_callback;
 } coreapp_header_t;
 
-// Initializes the coreapp applet structure
-void coreapp_init(applet_t* applet);
+#ifdef TREZOR_EMULATOR
 
-// Resets the coreapp and prepares it for execution from its entry point.
+// Initializes the coreapp and prepares it for execution from its entry point.
 //
 // Coreapp does not start immediately, it needs to be run by
 // `applet_run()` after calling this function.
 //
-// Returns `true` if the applet was successfully reset.
-bool coreapp_reset(applet_t* applet, uint32_t cmd, const void* arg,
-                   size_t arg_size);
+// Returns `true` if the applet was successfully initialized.
+bool coreapp_init(applet_t* applet, int argc, char** argv);
+
+#else
+
+// Initializes the coreapp and prepares it for execution from its entry point.
+//
+// Coreapp does not start immediately, it needs to be run by
+// `applet_run()` after calling this function.
+//
+// Returns `true` if the applet was successfully initialized.
+bool coreapp_init(applet_t* applet, uint32_t cmd, const void* arg,
+                  size_t arg_size);
 
 mpu_area_t coreapp_get_code_area(void);
 
 mpu_area_t coreapp_get_tls_area(void);
 
+#endif  // TREZOR_EMULATOR
+
 #endif  // KERNEL_MODE
diff --git a/core/embed/sys/task/stm32/coreapp.c b/core/embed/sys/task/stm32/coreapp.c
index 48abf1422..5b2c071b3 100644
--- a/core/embed/sys/task/stm32/coreapp.c
+++ b/core/embed/sys/task/stm32/coreapp.c
@@ -36,8 +36,17 @@ static mpu_area_t coreapp_tls_area;
 extern uint32_t _kernel_flash_end;
 #define KERNEL_END ALIGN_UP((uint32_t) & _kernel_flash_end, COREAPP_ALIGNMENT)
 
-// Initializes coreapp applet
-void coreapp_init(applet_t* applet) {
+static void coreapp_clear_memory(applet_t* applet) {
+  if (applet->layout.data1.size > 0) {
+    memset((void*)applet->layout.data1.start, 0, applet->layout.data1.size);
+  }
+  if (applet->layout.data2.size > 0) {
+    memset((void*)applet->layout.data2.start, 0, applet->layout.data2.size);
+  }
+}
+
+bool coreapp_init(applet_t* applet, uint32_t cmd, const void* arg,
+                  size_t arg_size) {
   const uint32_t CODE1_START = KERNEL_END;
 
 #ifdef FIRMWARE_P1_START
@@ -66,19 +75,7 @@ void coreapp_init(applet_t* applet) {
   };
 
   applet_init(applet, &coreapp_layout, &coreapp_privileges);
-}
-
-static void coreapp_clear_memory(applet_t* applet) {
-  if (applet->layout.data1.size > 0) {
-    memset((void*)applet->layout.data1.start, 0, applet->layout.data1.size);
-  }
-  if (applet->layout.data2.size > 0) {
-    memset((void*)applet->layout.data2.start, 0, applet->layout.data2.size);
-  }
-}
 
-bool coreapp_reset(applet_t* applet, uint32_t cmd, const void* arg,
-                   size_t arg_size) {
   // Enable access to coreapp memory regions
   mpu_set_active_applet(&applet->layout);
 
diff --git a/core/embed/sys/task/unix/coreapp.c b/core/embed/sys/task/unix/coreapp.c
new file mode 100644
index 000000000..b0368e1e5
--- /dev/null
+++ b/core/embed/sys/task/unix/coreapp.c
@@ -0,0 +1,48 @@
+/*
+ * This file is part of the Trezor project, https://trezor.io/
+ *
+ * Copyright (c) SatoshiLabs
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifdef KERNEL
+
+#include <trezor_rtl.h>
+
+#include <sys/applet.h>
+#include <sys/coreapp.h>
+#include <sys/systask.h>
+
+extern int coreapp_emu(int argc, char** argv);
+
+bool coreapp_init(applet_t* applet, int argc, char** argv) {
+  const applet_layout_t coreapp_layout = {0};
+  const applet_privileges_t coreapp_privileges = {0};
+
+  applet_init(applet, &coreapp_layout, &coreapp_privileges);
+
+  if (!systask_init(&applet->task, 0, 0, 0, applet)) {
+    return false;
+  }
+
+  if (!systask_push_call(&applet->task, (void*)coreapp_emu, (uintptr_t)argc,
+                         (uintptr_t)argv, 0)) {
+    return false;
+  }
+
+  return true;
+}
+
+#endif  // KERNEL
diff --git a/core/site_scons/models/unix_common.py b/core/site_scons/models/unix_common.py
index b02be0198..9e9879e50 100644
--- a/core/site_scons/models/unix_common.py
+++ b/core/site_scons/models/unix_common.py
@@ -98,4 +98,8 @@ def unix_common_files(env, features_wanted, defines, sources, paths):
         defines += [("USE_IPC", "1")]
         paths += ["embed/sys/ipc/inc"]
 
+    if "applet" in features_wanted:
+        sources += ["embed/sys/task/unix/applet.c"]
+        sources += ["embed/sys/task/unix/coreapp.c"]
+
     return features_available