core-image-tiny: Provide a new image recipe for poky-tiny that boots from RAM

This new image recipe creates an image from the artifacts
obtained after building core-image-tiny-initramfs, it boots
directly to a tiny rootfs provided by initrd

Signed-off-by: Alejandro Hernandez <alejandro.hernandez@linux.intel.com>

common/recipes-core/images/core-image-tiny-initramfs.bbappend

@@ -1,11 +0,0 @@
-# Set WKS file depending on the MACHINE picked by the user applies 
-# only when using an Intel MACHINE, otherwise leaves it as it is.
-
-python (){
-    if d.getVar('MACHINE', True) == "intel-core2-32":
-        d.setVar('WKS_FILE', "systemd-bootdisk-tiny32.wks")
-    elif d.getVar('MACHINE', True) == "intel-corei7-64":
-        d.setVar('WKS_FILE', "systemd-bootdisk-tiny64.wks")
-    elif d.getVar('MACHINE', True) == "intel-quark":
-        d.setVar('WKS_FILE', "mktinygalileodisk.wks")
-}

common/recipes-core/images/core-image-tiny.bb

@@ -0,0 +1,37 @@
+SUMMARY = "A tiny image just capable of allowing a device to boot from RAM, \
+this image recipe generates an image file which rather boots from initrd than \
+from storage, it achieves this by using wic to pick up the artifacts generated \
+by the core-image-tiny-initramfs image"
+
+# The actual rootfs/initrd will be the one from core-image-tiny-initramfs, so
+# we reset IMAGE_INSTALL to avoid building other things that will be pointless
+IMAGE_INSTALL = ""
+
+# Do not pollute the initrd image with rootfs features
+IMAGE_FEATURES = ""
+
+IMAGE_LINGUAS = " "
+
+LICENSE = "MIT"
+
+IMAGE_ROOTFS_SIZE ?= "8192"
+
+IMAGE_FSTYPES = "wic"
+inherit core-image
+
+# We get some parts from image-live that we need in order to boot from initrd
+INITRD_IMAGE_LIVE ?= "core-image-tiny-initramfs"
+
+python() {
+    image_b = d.getVar('IMAGE_BASENAME')
+    initrd_i = d.getVar('INITRD_IMAGE_LIVE')
+    if image_b == initrd_i:
+        bb.error('INITRD_IMAGE_LIVE %s cannot use the requested IMAGE_FSTYPE' % initrd_i)
+        bb.fatal('Check IMAGE_FSTYPES and INITRAMFS_FSTYPES settings.')
+    elif initrd_i:
+        d.appendVarFlag('do_image', 'depends', ' %s:do_image_complete' % initrd_i)
+}
+
+WKS_FILE_intel-corei7-64 = "core-image-tiny.wks.in"
+WKS_FILE_intel-core2-32 = "core-image-tiny.wks.in"
+WKS_FILE_intel-quark = "mktinygalileodisk.wks"

wic/core-image-tiny.wks.in

@@ -1,9 +1,9 @@
-# short-description: Create an EFI disk image with systemd-boot and corei7-64
+# short-description: Create an EFI disk image with systemd-boot and corei7-64/core2-32
 # long-description: Creates a partitioned EFI disk image that the user
 # can directly dd to boot media. The selected bootloader is systemd-boot.
-# This disk image is meant to be used by corei7-64 and core-image-tiny-initramfs
+# This disk image is meant to be used by corei7-64/core2-32 and core-image-tiny-initramfs
 
-part /boot --source bootimg-efi --sourceparams="loader=systemd-boot,initrd=core-image-tiny-initramfs-intel-corei7-64.cpio.gz" --ondisk sda --label msdos --active --align 1024
+part /boot --source bootimg-efi --sourceparams="loader=systemd-boot,initrd=core-image-tiny-initramfs-${MACHINE}.cpio.gz" --ondisk sda --label msdos --active --align 1024
 
 bootloader --ptable gpt --timeout=5 --append="init=/bin/busybox sh init console=ttyS0,115200 console=tty0 rw LABEL=boot debugshell=5"
 

wic/systemd-bootdisk-tiny32.wks

@@ -1,8 +0,0 @@
-# short-description: Create an EFI disk image with systemd-boot and core2-32
-# long-description: Creates a partitioned EFI disk image that the user
-# can directly dd to boot media. The selected bootloader is systemd-boot.
-# This disk image is meant to be used by core2-32 and core-image-tiny-initramfs
-
-part /boot --source bootimg-efi --sourceparams="loader=systemd-boot,initrd=core-image-tiny-initramfs-intel-core2-32.cpio.gz" --ondisk sda --label msdos --active --align 1024
-
-bootloader --ptable gpt --timeout=5 --append="init=/bin/busybox sh init console=ttyS0,115200 console=tty0 rw LABEL=boot debugshell=5"