Hi,
with this change my rock-pi-4 doesnt boot up and falls to emergency shell because wic includes wrong devices into fstab. For some reason it assumes /dev/sda1. I was able to fix this for my machine by using uuid for all partitions.
diff --git a/wic/rockchip.wks b/wic/rockchip.wks
index 5ee276b..90bdb27 100644
--- a/wic/rockchip.wks
+++ b/wic/rockchip.wks
@@ -15,12 +15,12 @@
 #   boot        32768           229376
 #   root        262144          -           (suggested)
-part loader1    --offset 32     --fixed-size 4000K --source rawcopy --sourceparams="file=${SPL_BINARY}"
-part reserved1  --offset 4032   --fixed-size 64K
-part reserved2  --offset 4096   --fixed-size 4096K
-part loader2    --offset 8192   --fixed-size 4096K --source rawcopy --sourceparams="file=u-boot.${UBOOT_SUFFIX}"
-part atf        --offset 12288  --fixed-size 4096K
-part /boot      --offset 16384  --size       114688K --active --source bootimg-partition --fstype=vfat --label boot --sourceparams="loader=u-boot"
-part / --source rootfs            --fstype=ext4 --label root --use-uuid
+part loader1   --offset 32 --fixed-size 4000K --source rawcopy --sourceparams="file=${SPL_BINARY}" --use-uuid
+part reserved1 --offset 4032 --fixed-size 64K --use-uuid
+part reserved2 --offset 4096 --fixed-size 4096K --use-uuid
+part loader2   --offset 8192 --fixed-size 4096K --source rawcopy --sourceparams="file=u-boot.${UBOOT_SUFFIX}" --use-uuid
+part atf       --offset 12288 --fixed-size 4096K --use-uuid
+part /boot     --offset 16384 --size 114688K --active --source bootimg-partition --fstype=vfat --label boot --sourceparams="loader=u-boot" --use-uuid
+part /         --source rootfs --fstype=ext4 --label root --use-uuid
-bootloader --ptable gpt --append="console=tty1 console=${RK_CONSOLE_DEVICE},${RK_CONSOLE_BAUD}n8 rw rootfstype=ext4 init=/sbin/init"
+bootloader     --ptable gpt --append="console=tty1 console=${RK_CONSOLE_DEVICE},${RK_CONSOLE_BAUD}n8 rw rootfstype=ext4 init=/sbin/init"
In addition i added an option that avoids editing fstab by wic at all since the image also boots without mounting /boot, but i guess this is just a matter of taste.
diff --git a/conf/machine/include/rockchip-wic.inc b/conf/machine/include/rockchip-wic.inc
index 15010a0..30b0d57 100644
--- a/conf/machine/include/rockchip-wic.inc
+++ b/conf/machine/include/rockchip-wic.inc
@@ -26,3 +26,6 @@ WICVARS:append = " \
        SPL_BINARY \
        UBOOT_SUFFIX \
        "
+
+# Do not update fstab file while creating wic images
+WIC_CREATE_EXTRA_ARGS ?= "--no-fstab-update"

Am 18.09.21 um 00:01 schrieb Trevor Woerner:

Recent upstream kernel changes have made the mmc probing order unpredictable.
Therefore, boards with both an emmc and sdmmc interface aren't guaranteed to
boot with a hard-coded root device selected.

For example, on the rock64, with linux-yocto 5.10.y, using the uSD card (i.e.
the sdmmc interface) about 50% of the time the boot would succeed, and roughly
50% of the time it wouldn't:

...
[ 0.612233] Waiting for root device /dev/mmcblk1p7...
[ 0.634551] mmc_host mmc1: Bus speed (slot 0) = 300000Hz (slot req 300000Hz, actual 300000HZ div = 0)
[ 0.639064] mmc_host mmc0: Bus speed (slot 0) = 50000000Hz (slot req 50000000Hz, actual 50000000HZ di)
[ 0.640007] mmc0: new high speed SDXC card at address 5048
[ 0.641176] mmcblk0: mmc0:5048 SD64G 58.0 GiB
[ 0.647610] random: fast init done
[ 0.648279] GPT:Primary header thinks Alt. header is not at the end of the disk.
[ 0.648941] GPT:376479 != 121634815
[ 0.649252] GPT:Alternate GPT header not at the end of the disk.
[ 0.649796] GPT:376479 != 121634815
[ 0.650106] GPT: Use GNU Parted to correct GPT errors.
[ 0.650598] mmcblk0: p1 p2 p3 p4 p5 p6 p7

NOTE the discrepancy between the kernel waiting for device /dev/mmcblk1p7,
which comes from the hard-coded kernel cmdline, and the kernel probing putting
the sdmmc on mmcblk0.

With linux-yocto 5.13.y on the rock64 using the uSD card the board would never
boot, the sdmmc always appears on mmcblk0.

Instead of simply changing the hard-coded root device (i.e. from mmcblk0 to
mmcblk1) switch to using partition UUIDs instead. Hard-coding the boot device
would work with 5.13.y but would fail 50% of the time with 5.10.y; who knows
what other kernels will do?

In any case, switching to UUIDs works regardless of board, kernel, or
available mmc interfaces.

Boot tested on:
- rock64
- nanopi-m4-2gb
- tinker-board
- rock-pi-e
- rock-pi-4b

Signed-off-by: Trevor Woerner<twoerner@...>
---
conf/machine/include/nanopi-m4.inc | 2 --
conf/machine/include/rock-pi-4.inc | 2 --
conf/machine/include/rockchip-wic.inc | 4 ----
conf/machine/rock64.conf | 3 ---
conf/machine/tinker-board-s.conf | 2 --
conf/machine/vyasa-rk3288.conf | 2 --
wic/rockchip.wks | 16 ++++++++--------
7 files changed, 8 insertions(+), 23 deletions(-)

diff --git a/conf/machine/include/nanopi-m4.inc b/conf/machine/include/nanopi-m4.inc
index ac6479d..3870b51 100644
--- a/conf/machine/include/nanopi-m4.inc
+++ b/conf/machine/include/nanopi-m4.inc
@@ -7,5 +7,3 @@ MACHINE_FEATURES += "usbhost serial"
KMACHINE = "nanopi-m4"
KERNEL_DEVICETREE = "rockchip/rk3399-nanopi-m4.dtb"
-
-RK_BOOT_DEVICE = "mmcblk1"
diff --git a/conf/machine/include/rock-pi-4.inc b/conf/machine/include/rock-pi-4.inc
index b6fb3dd..0a86846 100644
--- a/conf/machine/include/rock-pi-4.inc
+++ b/conf/machine/include/rock-pi-4.inc
@@ -3,6 +3,4 @@ MACHINEOVERRIDES =. "rock-pi-4:"
require conf/machine/include/rk3399.inc
-RK_BOOT_DEVICE = "mmcblk1"
-
MACHINE_EXTRA_RRECOMMENDS += "kernel-modules"
diff --git a/conf/machine/include/rockchip-wic.inc b/conf/machine/include/rockchip-wic.inc
index b5939f7..15010a0 100644
--- a/conf/machine/include/rockchip-wic.inc
+++ b/conf/machine/include/rockchip-wic.inc
@@ -20,11 +20,7 @@ IMAGE_BOOT_FILES = " \
RK_CONSOLE_BAUD ?="${@d.getVar('SERIAL_CONSOLES').split(';')[0]}"
RK_CONSOLE_DEVICE ?="${@d.getVar('SERIAL_CONSOLES').split(';')[1].split()[0]}"
-# boot device (sd-card/emmc)
-RK_BOOT_DEVICE ??= "mmcblk0"
-
WICVARS:append = " \
- RK_BOOT_DEVICE \
RK_CONSOLE_BAUD \
RK_CONSOLE_DEVICE \
SPL_BINARY \
diff --git a/conf/machine/rock64.conf b/conf/machine/rock64.conf
index 21755a8..fa75a51 100644
--- a/conf/machine/rock64.conf
+++ b/conf/machine/rock64.conf
@@ -12,7 +12,4 @@ MACHINE_FEATURES += "usbhost serial"
UBOOT_MACHINE = "rock64-rk3328_defconfig"
KERNEL_DEVICETREE = "rockchip/rk3328-rock64.dtb"
-# set to mmcblk0 for booting from optional eMMC
-RK_BOOT_DEVICE ?= "mmcblk1"
-
KBUILD_DEFCONFIG = "defconfig"
diff --git a/conf/machine/tinker-board-s.conf b/conf/machine/tinker-board-s.conf
index 9f44f2f..870b9bc 100644
--- a/conf/machine/tinker-board-s.conf
+++ b/conf/machine/tinker-board-s.conf
@@ -9,5 +9,3 @@ require conf/machine/include/tinker.inc
KERNEL_DEVICETREE = "rk3288-tinker-s.dtb"
UBOOT_MACHINE = "tinker-s-rk3288_defconfig"
-
-RK_BOOT_DEVICE ?= "mmcblk1"
diff --git a/conf/machine/vyasa-rk3288.conf b/conf/machine/vyasa-rk3288.conf
index 9ad1ed4..5b44257 100644
--- a/conf/machine/vyasa-rk3288.conf
+++ b/conf/machine/vyasa-rk3288.conf
@@ -13,5 +13,3 @@ KERNEL_DEVICETREE = "rk3288-vyasa.dtb"
KERNEL_EXTRA_ARGS += "LOADADDR=0x02000000"
UBOOT_MACHINE = "vyasa-rk3288_defconfig"
-
-RK_BOOT_DEVICE = "mmcblk2"
diff --git a/wic/rockchip.wks b/wic/rockchip.wks
index eedae0d..5ee276b 100644
--- a/wic/rockchip.wks
+++ b/wic/rockchip.wks
@@ -15,12 +15,12 @@
# boot 32768 229376
# root 262144 - (suggested)
-part loader1 --offset 32 --fixed-size 4000K --ondisk ${RK_BOOT_DEVICE} --source rawcopy --sourceparams="file=${SPL_BINARY}"
-part reserved1 --offset 4032 --fixed-size 64K --ondisk ${RK_BOOT_DEVICE}
-part reserved2 --offset 4096 --fixed-size 4096K --ondisk ${RK_BOOT_DEVICE}
-part loader2 --offset 8192 --fixed-size 4096K --ondisk ${RK_BOOT_DEVICE} --source rawcopy --sourceparams="file=u-boot.${UBOOT_SUFFIX}"
-part atf --offset 12288 --fixed-size 4096K --ondisk ${RK_BOOT_DEVICE}
-part /boot --offset 16384 --size 114688K --active --ondisk ${RK_BOOT_DEVICE} --source bootimg-partition --fstype=vfat --label boot --sourceparams="loader=u-boot"
-part / --ondisk ${RK_BOOT_DEVICE} --source rootfs --fstype=ext4 --label root
+part loader1 --offset 32 --fixed-size 4000K --source rawcopy --sourceparams="file=${SPL_BINARY}"
+part reserved1 --offset 4032 --fixed-size 64K
+part reserved2 --offset 4096 --fixed-size 4096K
+part loader2 --offset 8192 --fixed-size 4096K --source rawcopy --sourceparams="file=u-boot.${UBOOT_SUFFIX}"
+part atf --offset 12288 --fixed-size 4096K
+part /boot --offset 16384 --size 114688K --active --source bootimg-partition --fstype=vfat --label boot --sourceparams="loader=u-boot"
+part / --source rootfs --fstype=ext4 --label root --use-uuid
-bootloader --ptable gpt --append="console=tty1 console=${RK_CONSOLE_DEVICE},${RK_CONSOLE_BAUD}n8 rw root=/dev/${RK_BOOT_DEVICE}p7 rootfstype=ext4 init=/sbin/init"
+bootloader --ptable gpt --append="console=tty1 console=${RK_CONSOLE_DEVICE},${RK_CONSOLE_BAUD}n8 rw rootfstype=ext4 init=/sbin/init"