vm_arm: inline memory initializtion module

- inline code from the module to simplify VMM. Rationale is that most
  VM will have this kind of fixed memory, so there is no gain if this
  is a module
- support make this kind of memory optional, don't even create a DTB
  node if size is 0
- improve comments

Signed-off-by: Axel Heider <[email protected]>

arm_vm_helpers.cmake

@@ -49,7 +49,6 @@ function(DeclareCAmkESARMVM init_component)
     )
 
     list(APPEND vm_src ${ARM_VM_PROJECT_DIR}/components/VM_Arm/src/modules/map_frame_hack.c)
-    list(APPEND vm_src ${ARM_VM_PROJECT_DIR}/components/VM_Arm/src/modules/init_ram.c)
 
     if(VmVirtUart)
         list(APPEND vm_src ${ARM_VM_PROJECT_DIR}/components/VM_Arm/src/modules/vuart_init.c)

components/VM_Arm/src/main.c

@@ -637,10 +637,26 @@ int install_vm_devices(vm_t *vm)
 {
     int err;
 
-    /* Install virtual devices */
     if (config_set(CONFIG_VM_PCI_SUPPORT)) {
         err = vm_install_vpci(vm, io_ports, pci);
-        assert(!err);
+        if (err) {
+            ZF_LOGE("Failed to install VPCI device");
+            return -1;
+        }
+    }
+
+    /* Install and initialize guest RAM. There might be no memory here, because
+     * this is the exclusive fixed guest memory. Modules may set up other forms
+     * of guest memory, e.g. memory shared with other VM and memory that is
+     * mapped on demand.
+     */
+    if (ram_size > 0) {
+        err = vm_ram_register_at(vm, ram_base, ram_size,
+                                 vm->mem.map_one_to_one);
+        if (err) {
+            ZF_LOGE("Failed to install RAM");
+            return -1;
+        }
     }
 
     int max_vmm_modules = (int)(__stop__vmm_module - __start__vmm_module);
@@ -775,8 +791,11 @@ static int generate_fdt(vm_t *vm, void *fdt_ori, void *gen_fdt, int buf_size, si
         return -1;
     }
 
-    /* generate a memory node (ram_base and ram_size) */
-    err = fdt_generate_memory_node(gen_fdt, ram_base, ram_size);
+    /* Generate a memory node. This is done even if ram_size is zero, so there
+     * is a guarantee that the DTB has a memory node.
+     */
+    err = fdt_generate_memory_node(gen_fdt, (ram_size > 0) ? ram_base : 0,
+                                   ram_size);
     if (err) {
         ZF_LOGE("Couldn't generate memory_node (%d)\n", err);
         return -1;