Enable either ext2, initrd or initramfs for x86, arm and aarch64

Mention that initrd and initramfs must fit into memory.

Fix missing stdout when ./run -d is used.

Ignore ./run -n for non x86.

build

@@ -12,11 +12,14 @@ linux_kernel_custom_config_file=''
 post_script_args=''
 qemu_sdl='--enable-sdl --with-sdlabi=2.0'
 v=0
-while getopts 'a:c:Cgj:i:kK:lp:qS:v' OPT; do
+while getopts 'a:b:c:Cgj:IiKk:lp:qS:v' OPT; do
   case "$OPT" in
     a)
       arch="$OPTARG"
     ;;
+    b)
+      config_fragments="$config_fragments $OPTARG"
+    ;;
     c)
       echo "$OPTARG" >> br2_cli
     ;;
@@ -26,11 +29,22 @@ while getopts 'a:c:Cgj:i:kK:lp:qS:v' OPT; do
     g)
       gem5=true
     ;;
-    j)
-      j="$OPTARG"
+    I)
+      echo "
+BR2_TARGET_ROOTFS_CPIO=n
+BR2_TARGET_ROOTFS_EXT2=n
+BR2_TARGET_ROOTFS_INITRAMFS=y
+" >> br2_cli
     ;;
     i)
-      config_fragments="$config_fragments $OPTARG"
+      echo "
+BR2_TARGET_ROOTFS_CPIO=y
+BR2_TARGET_ROOTFS_EXT2=n
+BR2_TARGET_ROOTFS_INITRAMFS=n
+" >> br2_cli
+    ;;
+    j)
+      echo "$OPTARG" >> br2_cli
     ;;
     k)
       extra_make_args="$extra_make_args kernel_module-reconfigure"