Add support for setting initial ramdisk

flouthoc · flouthoc · commit 4bccbdd18344 · 2021-07-26T14:33:53.000+05:30
diff --git a/src/kernel.c b/src/kernel.c
@@ -68,6 +68,31 @@ void *kernel_load(struct vm *vm, char *path) {
   kernel_size = image_size - offset_kernel;
 
   memcpy(ram_addr + 0x100000, mem + offset_kernel, kernel_size);
+
+  // load initramfs
+  if (vm->initramfs != NULL) {
+    int fd_initram = open(vm->initramfs, O_RDWR);
+    if (fd_initram < -1)
+      err(1, "open initramfs image failed");
+
+    struct stat statbuf;
+    fstat(fd_initram, &statbuf);
+    size_t initram_size = statbuf.st_size;
+
+    uint8_t *init_memory = mmap(NULL, initram_size, PROT_READ | PROT_WRITE,
+                                MAP_SHARED, fd_initram, 0);
+    if (init_memory == MAP_FAILED)
+      errx(1, "initramfs: failed loading image");
+
+    memcpy(ram_addr + kernel_size + 0x100000, init_memory, statbuf.st_size);
+    struct boot_params *initramfs_boot_param =
+        (struct boot_params *)(ram_addr + 0x6000 + 0x10000);
+    struct setup_header *setup_header = &(initramfs_boot_param->hdr);
+
+    setup_header->ramdisk_image = (uint64_t)(kernel_size + 0x100000);
+    setup_header->ramdisk_size = statbuf.st_size;
+  }
+
   return ram_addr;
 }
 
diff --git a/src/vm.h b/src/vm.h
@@ -13,6 +13,7 @@ struct vm {
   size_t ram_size;
   struct kvm_run *run;
   struct kvm_sregs sregs;
+  char *initramfs;
 };
 
 int vm_create(struct vm *v);
diff --git a/src/wiser.c b/src/wiser.c
@@ -34,12 +34,14 @@ static struct argp_option options[] = {
     {"memory", 'r', 0, 0, "Ram size for your vm"},
     {"vcpu", 'c', 0, 0, "Number of cpu for your vm"},
     {"image", 'i', "IMAGE", 0, "linux kernel bzimage"},
+    {"initramfs", 'z', "PATH", 0, "load initial ram disk"},
     {0}};
 
 /* Used by main to communicate with parse_opt. */
 struct arguments {
   int verbose, memory, vcpu;
   char *image_file;
+  char *initrd_file;
 };
 
 /* Parse a single option. */
@@ -55,6 +57,9 @@ static error_t parse_opt(int key, char *arg, struct argp_state *state) {
   case 'i':
     arguments->image_file = arg;
     break;
+  case 'z':
+    arguments->initrd_file = arg;
+    break;
   case 'c':
     arguments->vcpu = atoi(arg); /* TODO */
   case 'r':
@@ -80,6 +85,9 @@ int main(int argc, char **argv) {
   int ret;
   struct vm core_vm;
 
+  if (arguments.initrd_file != NULL)
+    core_vm.initramfs = arguments.initrd_file;
+
   ret = vm_create(&core_vm);
   ERROR(ret)
   ret = vm_init(&core_vm);
