Booting Radxa rock-3a using a btrfs volume in a nvme disk

[Jose Luis]

Hi,

 

I've a rock-3a board with an NVMe device and a BTRFS filesystem using the whole disk ( no partitions )

 

I've seen some devices having BTRFS support in u-boot, so first thing I built the u-boot images using the extension:

 

cat extensions/uboot-btrfs.sh
# Enable BTRFS support in u-boot

function post_config_uboot_target__enable_uboot_btrfs_support() {
display_alert "u-boot for ${BOARD}/${BRANCH}" "u-boot: enable BTRFS filesystem support" "info"
run_host_command_logged scripts/config --enable CONFIG_CMD_BTRFS
}

 

And patched the configuration of the board:

 

git diff .
diff --git a/config/boards/rock-3a.conf b/config/boards/rock-3a.conf
index 401894fa5..90f8a8a72 100644
--- a/config/boards/rock-3a.conf
+++ b/config/boards/rock-3a.conf
@@ -15,12 +15,15 @@ BOOT_SPI_RKSPI_LOADER="yes"
IMAGE_PARTITION_TABLE="gpt"
BOOTFS_TYPE="fat"

+# Enable btrfs support in u-boot
+enable_extension "uboot-btrfs"
+
function post_family_config__rock-3a_use_mainline_uboot_except_vendor_and_add_sata_target() {
display_alert "$BOARD" "Configuring ($BOARD) standard and sata uboot target map" "info"
UBOOT_TARGET_MAP="

 

 

./compile.sh artifact BOARD=rock-3a BRANCH=current RELEASE=trixie BUILD_MINIMAL=yes BUILD_DESKTOP=no KERNEL_CONFIGURE=no COMPRESS_OUTPUTIMAGE=sha,img ROOTFS_TYPE=btrfs FIXED_IMAGE_SIZE=4096 DISABLE_IPV6=false WHAT=uboot

  

With this I flashed the SPI image:

 

root@rock-3a:~# flashcp u-boot-rockchip-spi.bin  /dev/mtd0

root@rock-3a:~# cat /proc/mtd
dev:    size   erasesize  name
mtd0: 01000000 00001000 "spi4.0"

 

So, then I booted it without the SD card I use for the /boot partition, used the serial port ( as it didn't autoboot )  and I saw:

 

=> nvme info
Device 0: Vendor: 0x2646 Rev: SBM02103 Prod: 50026B778514A843 e: Hard Disk
Capacity: 953869.7 MB = 931.5 GB (1953525168 x 512)


=> btrsubvol nvme 0:1
** No partition table - nvme 0 **
Couldn't find partition nvme 0:1
=> btrsubvol nvme 0:0
ID 257 gen 153600 path /@rootfs/
ID 257 gen 153600 path /@rootfs/
ID 259 gen 153599 path /@home/

=> ls nvme 0:0 /boot/
<DIR>         16  Sat Dec 06 08:32:08 2025  dtb
<   >          0  Sat Dec 06 08:44:38 2025  .next
<   >   37679616  Sat Nov 15 03:03:00 2025  Image
<   >    5560276  Tue Nov 11 22:48:14 202urrent-rockchip64
<   >    5560445  Sat Nov 15 03:03:00 2025  System.map-6.12.58-current-rockchip64
<   >        236  Sat Dec 06 08:54:54 2025  armbianEnv.txt<   >        200  Sat Sep 09 08:armbianEnv.txt.old
<   >          0  Tue Jun 18 18:05:14 2024  armbianEnv.txt.out
<   >       1536  Thu Aug 31 17:25:06 2023  armbian_first_run.txt.template
<   >      38518  Thu Aug 31 17:25:04 2023  boot.bmp
<   >       3180  Thu Aug 31 17:20:00 2023  boot.cmd
<   >       3252  Thu Aug 31 17:26:44 20  boot.scr
<   >     258746  Tue Nov 11 22:48:14 2025  config-6.12.57-current-rockchip64
<   >     258803  Sat Nov 15 03:03:00 2025  config-6.12.58-current-ro<   >   29107600  Tue Nov 25 21:2 2025  initrd.img-6.12.57-current-rockchip64
<   >   29108356  Sat Dec 06 08:44:34 2025  initrd.img-6.12.58-current-rockchip64<   >   29108420  Sat Dec 06 08:
  

 

So it can read BTRFS, but no booting, I tried manually based on some commands I get but no luck:

 

=> load nvme 0:0 $loadaddr /boot/boot.scr
3252 bytes read in 27 ms (117.2 KiB/s)

=> source
## Executing script at 00c00800
Boot script loaded from
** Bad device specification 0x9000000 armbianEnv **
** Bad device specification 0x9000000 armbianEnv.txt **
Couldn't find partit
Can't set block device
** Bad device specification 0x12180000 uInitrd **
** Bad device specification 0x12180000 uInitrd **
Couldn't find partition 0x1218000ck device
** Bad device specification 0x02000000 Image **
** Bad device specification 0x020000on 0x02000000 Image
Can't set block device
** Bad device specification 0x12000000 dtb/rockchipspecification 0x12000000 dtb/rockchip/rk3568-rock-3a.dtb **
Couldn't find partition 0x12000000 t set block device
libfdt fdt_check_header(): FDT_ERR_BADMAGIC
No FDT memory address configure via "fdt addr <address>" command.
Aborting!
** Bad device specification 0x9000000 dtb/rockchiay/-fixup **
** Bad device specification 0x9000000 dtb/rockchip/overlay/-fixup.scr **
Couldn'tp/overlay/-fixup.scr
Can't set block device
** Bad device specification 0x9000000 fixup **
**0 fixup.scr **
Couldn't find partition 0x9000000 fixup.scr
Can't set block device
Applying us
## Executing script at 09000000
Wrong image format for "source" command
Unknown command 'kaslRM64 Image magic!

 

I'd like to get this worked, I can test anything you can provide me, I'm a n00b trying to learn a bit more about U-Boot.

 

Thanks in advance. 

 

 

[eselarm]

Your serial console cable seems to drop several characters or so, but that should not matter for booting.

 

What matters I think is that you have no partition and I see in boot.cmd

test -n "${distro_bootpart}" || distro_bootpart=1

echo "Boot script loaded from ${devtype} ${devnum}:${distro_bootpart}"

 

This 1 year old, yours might be different.  So if your boot.scr is still compiled from such boot.cmd content (see end of file how), I think it won't work. I have used parttitionless Btrfs, but not for OS rootfs, I also think GRUB will need a hack then. So if possible make it with just as default as possible, a 1st partition btrfs formatted with rootfs and likely also the rootfs subvol set as default. Also that is a tricky thing with GRUB (Debian) I know. I wiped a bootFAT partition actually, so about 16M+256M space before rootfs partition and also sorted the GPT table to default, so 1st entry Btrfs rootfs.

 

I find the boot cmd rather complex, I used a minimum direct one as well for tests. see 

 

My (ROCK3A 24/7 up now) has bootFAT again, I did wipe/hide boot.* and armbianEnv.txt and use extlinux, so I can select a specific kernel option via serial console.

 

/extlinux/extlinux.conf

menu title Select the kernel variant
DEFAULT vendor
TIMEOUT 80
LABEL vendor
       KERNEL 6.1.115-vendor-rk35xx/Image
       INITRD 6.1.115-vendor-rk35xx/uInitrd
       FDT    6.1.115-vendor-rk35xx/rk3568-rock-3a.dtb
       FDTOVERLAYS 6.1.115-vendor-rk35xx/rock-3a-sata.dtbo
       APPEND root=LABEL=armbidroot rootwait rw earlyprintk console=ttyS2,1500000 cma=256M
LABEL edge
       KERNEL 6.17.0-edge-rockchip64/Image
       INITRD 6.17.0-edge-rockchip64/uInitrd
       FDT    6.17.0-edge-rockchip64/rk3568-rock-3a.dtb
       APPEND root=LABEL=armbidroot rootwait rw earlyprintk console=ttyS2,1500000 cma=256M

As this is on extra FAT, I need extra copies for all the files referenced, but when only 1 Btrfs, it should be possible to refer to files in /boot and elsewhere.

Edited December 12, 2025 by eselarm

[Jose Luis]

Hi @eselarm, thanks for the detailed response.

 

I've checked my boot.cmd and boot.scr is ancient ( from Aug 2023 ).

 

I'm going to try to set the variables beforehand, as I see in the output they are blank ( devtype, devnum, prefix ). 

 

When I succeed I guess the next step will be to set these variables in U-Boot, but nowadays there's no gpt partition table in SPI with the uboot_env, so I guess will need to figure it out later ( via env or find the boot.scr in the NVMe ), first I want to try to boot from NVMe manually.

 

Thanks again

[Jose Luis]

Ok, I got it booting, so I did:

 

set devtype nvme
set devnum 0
set distro_bootpart 0
set prefix /boot/

load nvme 0:0 $loadaddr /boot/boot.scr
source

 

Doing a printenv before I see:

=> printenv
arch=arm
baudrate=1500000
board=evb_rk3568
board_name=evb_r_targets=mmc1 mmc0 nvme scsi usb pxe dhcp spi
bootcmd=bootflow scan -lb
bootdelay=1
bootp_arcNDI:003000
cpu=armv8
cpuid#=54434e4b383000000000000000070d19
dnsip=192.168.1.253
eth1addr=1e000
ethaddr=1e:f2:d5:f1:74:04
fdt_addr_r=0x12000000
fdtcontroladdr=7ded3a80
fdtfile=rockchipr=0x12100000
gatewayip=192.168.1.254
hostname=rock-3a
ipaddr=192.168.1.253
kernel_addr_r=0x00
kernel_comp_size=0x8000000
loadaddr=0xc00800
netmask=255.255.255.0
pxefile_addr_r=0x00e000offset_f=0xffe000
script_size_f=0x2000
scriptaddr=0x00c00000
serial#=09103e09ce4edd27
serverserial@fe660000
stdin=serial@fe660000
stdout=serial@fe660000
vendor=rockchip

Environment size: 916/126972 bytes

 

So this is not finding the boot.scr with the bootflow scan -lb, so now is time to make it boot automatically.

Edited December 19, 2025 by Jose Luis

[eselarm]

4 hours ago, Jose Luis said:

board=evb_rk3568

I am not sure if this will lead to problems. The SBC is a Radxa ROCK3A. It might be EVB was used for development and never changed. Maybe won't matter as later on kernel rock-3a dtb is loaded. But could be a reason for issues I saw (year ago) with mainline u-boot, therefor I use Radxa's one / legacy.

Edited December 19, 2025 by eselarm

[Jose Luis]

Well, I finally used some disk drives to move the btrfs data live, repartition with GPT using a vFAT and btrfs partition with 16MB offset of u-boot before the first partition, so with this boots automatically, and I guess more mainline.

 

Thanks @eselarm for your comments, I'll these variables later.