many: enable sysota for QEMU x86{,-64}

This branch enables SysOTA for the currently supported QEMU targets. ARM is not supported only because we don't have bootable disk-images for QEMU, not because of any inherent incompatibility.

Apart from MACHINE-specific configuration files for RAUC (that, for the moment, encode block device names and the COMPATIBLE) and SysOTA (that encode the MACHINE string) everything is entirely generic wherever GRUB is supported.

I've tested this, including boot, update and rollback for qemux86 and qemux86-64 MACHINEs.

This does duplicate some of the other branches I had open but perhaps it would be easier to evaluate as one piece. It depends on !570 (for some edge cases in case grubenv is damaged) and !569 (on x86_64).

zstd support is only required to update, the system will boot a vanilla image without this patch.

Even with this landed there are some TODOs that I've left out for another wave:

• Partition type UUIDs for SYS_A and SYS_B partitions in our wic images.
• GRUB's partition type UUID support will allow our GRUB boot script to be platform independent and no longer machine specific.
• Similar change to all the RAUC configuration files, so that they don't have to name block devices manually.
• Extending this to SECO x86 systems (we need similar MACHINE-specific patches and a test on a real board that I don't have at the moment, CC @ektor5) (This is now #482 (closed))
• Removing the kernel image from the EFI system partition - this is dead file that nothing references anymore. (This is now #483)

Closes: #70 (closed)

meta-oniro-core/recipes-bsp/grub/files/grub.cfg

@@ -7,6 +7,81 @@
 
 serial --unit=0 --speed=115200 --word=8 --parity=no --stop=1
 
-# Boot the "A" slot all the time. This file is a stub.
-linux "(hd0,gpt2)/boot/bzImage" root=/dev/sda2 rauc.slot=A $CMDLINE
+set CMDLINE="console=ttyS0,115200 panic=60 quiet"
+
+# Find the boot partition. We need to know where to load from and save the
+# environment to. The boot partition is saved into the ONIRO_GRUB_BOOT
+# variable.
+#
+# TODO: switch to out-of-tree search by partition type uuid.
+#
+# XXX: the boot string is hard-coded but the .wks file allows customization via
+# BOOT_PARTITION_LABEL, which is unsupported here.
+if search --label --set ONIRO_BOOT_PART --no-floppy --hint-efi=hd0,gpt1 boot; then
+    echo "note: found ONIRO_BOOT_PART=$ONIRO_BOOT_PART"
+else
+    echo "error: cannot find boot partition, halting"
+    halt
+fi
+
+# Load a specific list of GRUB variables from the grubenv file. Ideally we
+# would never have this and we would use EFI variables instead but this is not
+# supported by RAUC without opting out of using GRUB itself.
+load_env --skip-sig --file "(${ONIRO_BOOT_PART})/EFI/BOOT/grubenv" SYSOTA_BOOT_ACTIVE SYSOTA_BOOT_TRY SYSOTA_BOOT_TRIED
+echo "note: loaded SYSOTA_BOOT_ACTIVE=$SYSOTA_BOOT_ACTIVE SYSOTA_BOOT_TRY=$SYSOTA_BOOT_TRY SYSOTA_BOOT_TRIED=$SYSOTA_BOOT_TRIED"
+
+# Recover active slot if the file is corrupted.
+if [ -z "$SYSOTA_BOOT_ACTIVE" ]; then
+    echo "warning: SYSOTA_BOOT_ACTIVE is unset, attempting recovery"
+    if [ -e "(hd0,gpt2)/boot/bzImage" -a -e "(hd0,gpt3)/boot/bzImage" ]; then
+        # Both slots are available, pick the more recent slot.
+        # TODO: handle rollback prevention flags (how?)
+        if [ "(hd0,gpt2)/boot/bzImage" -nt "(hd0,gpt3)/boot/bzImage" ]; then
+            echo "note: recovered SYSOTA_BOOT_ACTIVE=A (slot A kernel is newer than slot B)"
+            set SYSOTA_BOOT_ACTIVE="A"
+        else
+            echo "note: recovered SYSOTA_BOOT_ACTIVE=B (slot B kernel is newer than slot A)"
+            set SYSOTA_BOOT_ACTIVE="B"
+        fi
+    elif [ -e "(hd0,gpt2)/boot/bzImage" ]; then
+        echo "note: recovered SYSOTA_BOOT_ACTIVE=A"
+        set SYSOTA_BOOT_ACTIVE="A"
+    elif [ -e "(hd0,gpt3)/boot/bzImage" ]; then
+        echo "note: recovered SYSOTA_BOOT_ACTIVE=B"
+        set SYSOTA_BOOT_ACTIVE="B"
+    else
+        echo "error: cannot recover GRUB environment block: both slots are corrupted, halting"
+        halt
+    fi
+
+    echo "note: saving recovered GRUB environment block"
+    save_env --file "($ONIRO_BOOT_PART)/EFI/BOOT/grubenv" SYSOTA_BOOT_ACTIVE SYSOTA_BOOT_TRY SYSOTA_BOOT_TRIED
+fi
+
+# Find the slot to boot from.
+if [ -n "$SYSOTA_BOOT_TRY" ]; then
+    echo "note: performing one-time boot from slot $SYSOTA_BOOT_TRY"
+    set SLOT="$SYSOTA_BOOT_TRY"
+    set SYSOTA_BOOT_TRIED="$SYSOTA_BOOT_TRY"
+    unset SYSOTA_BOOT_TRY
+
+    echo "note: saving modified GRUB environment block"
+    save_env --file "($ONIRO_BOOT_PART)/EFI/BOOT/grubenv" SYSOTA_BOOT_ACTIVE SYSOTA_BOOT_TRY SYSOTA_BOOT_TRIED
+else
+    echo "note: performing normal boot from slot $SYSOTA_BOOT_ACTIVE"
+    set SLOT="$SYSOTA_BOOT_ACTIVE"
+fi
+
+# Load the kernel from the rootfs partition corresponding to the slot.
+# See https://gitlab.eclipse.org/eclipse/oniro-core/sysota/-/wikis/Boot%20Assets%20Specification#efigrub
+if [ "$SLOT" == "A" ]; then
+    # TODO pass root partition by partuuid.
+    linux "(hd0,gpt2)/boot/bzImage" root=/dev/sda2 rauc.slot=A $CMDLINE
+elif [ "$SLOT" == "B" ]; then
+    linux "(hd0,gpt3)/boot/bzImage" root=/dev/sda3 rauc.slot=B $CMDLINE
+else
+    echo "error: cannot select slot to boot from, halting"
+    halt
+fi
+
 boot