ipq40xx: Support Chromium OS image-type creation

See firmware-utils.git commits [1], which implemented the cros-vbutil
verified-boot payload-packing tool, and extended ptgen for the CrOS
kernel partition type. With these, it's now possible to package kernel +
rootfs to make disk images that can boot a Chrome OS-based system (e.g.,
Chromebooks, or even a few AP models).

Regarding PARTUUID= changes: Chromium bootloaders work well with a
partition number offset (i.e., relative to the kernel partition), so
we'll be using a slightly different root UUID line.

NB: I've made this support specific to ip40xx for now, because I only
plan to support an IPQ4019-based AP that uses a Chromium-based
bootloader, but this image format can be used for essentially any
Chromebook, as well as the Google OnHub, a prior Chromium-based AP using
an IPQ8064 chipset.

[1]
ptgen: add Chromium OS kernel partition support
https://git.openwrt.org/?p=project/firmware-utils.git;a=commit;h=6c95945b5de973026dc6f52eb088d0943efa96bb

cros-vbutil: add Chrome OS vboot kernel-signing utility
https://git.openwrt.org/?p=project/firmware-utils.git;a=commit;h=8e7274e02fdc6f2cb61b415d6e5b2e1c7e977aa1

Signed-off-by: Brian Norris <computersforpeace@gmail.com>

diff --git a/package/base-files/files/lib/upgrade/common.sh b/package/base-files/files/lib/upgrade/common.sh
index 24ff77a8b3101e0ad1ee0f4b46ff626ecb1ce0f5..5af061f6a43990afea92f8eacd865fe5249d8300 100644 (file)
--- a/package/base-files/files/lib/upgrade/common.sh
+++ b/package/base-files/files/lib/upgrade/common.sh
@@ -155,9 +155,11 @@ export_bootdevice() {
                                fi
                        done
                ;;
+               PARTUUID=????????-????-????-????-??????????0?/PARTNROFF=1 | \
                PARTUUID=????????-????-????-????-??????????02)
                        uuid="${rootpart#PARTUUID=}"
-                       uuid="${uuid%02}00"
+                       uuid="${uuid%/PARTNROFF=1}"
+                       uuid="${uuid%0?}00"
                        for disk in $(find /dev -type b); do
                                set -- $(dd if=$disk bs=1 skip=568 count=16 2>/dev/null | hexdump -v -e '8/1 "%02x "" "2/1 "%02x""-"6/1 "%02x"')
                                if [ "$4$3$2$1-$6$5-$8$7-$9" = "$uuid" ]; then

diff --git a/target/linux/ipq40xx/image/chromium.mk b/target/linux/ipq40xx/image/chromium.mk
new file mode 100644 (file)
index 0000000..15d4c1a
--- /dev/null
+++ b/target/linux/ipq40xx/image/chromium.mk
@@ -0,0 +1,22 @@
+define Build/cros-gpt
+       cp $@ $@.tmp 2>/dev/null || true
+       ptgen -o $@.tmp -g \
+               -T cros_kernel  -N kernel -p $(CONFIG_TARGET_KERNEL_PARTSIZE)m \
+                               -N rootfs -p $(CONFIG_TARGET_ROOTFS_PARTSIZE)m
+       cat $@.tmp >> $@
+       rm $@.tmp
+endef
+
+define Build/append-kernel-part
+       dd if=$(IMAGE_KERNEL) bs=$(CONFIG_TARGET_KERNEL_PARTSIZE)M conv=sync >> $@
+endef
+
+# NB: Chrome OS bootloaders replace the '%U' in command lines with the UUID of
+# the kernel partition it chooses to boot from. This gives a flexible way to
+# consistently build and sign kernels that always use the subsequent
+# (PARTNROFF=1) partition as their rootfs.
+define Build/cros-vboot
+       $(STAGING_DIR_HOST)/bin/cros-vbutil \
+               -k $@ -c "root=PARTUUID=%U/PARTNROFF=1" -o $@.new
+       @mv $@.new $@
+endef