U-Boot Not Working on Raspberry Pi 5
Mikeyy M
heyitsmemikeyy at gmail.com
Thu Oct 23 12:12:51 CEST 2025
Hi Peter,
Thanks for your help. The SD card has a single large FAT32 partition. No
separate ext4 root filesystem partition has been created yet. Here are the
commands I ran on my SD card and their output:
michael at laptop:~$ sudo fdisk -l /dev/mmcblk0
> Disk /dev/mmcblk0: 59.48 GiB, 63864569856 bytes, 124735488 sectors
> Units: sectors of 1 * 512 = 512 bytes
> Sector size (logical/physical): 512 bytes / 512 bytes
> I/O size (minimum/optimal): 512 bytes / 512 bytes
> Disklabel type: dos
> Disk identifier: 0x00000000
> Device Boot Start End Sectors Size Id Type
> /dev/mmcblk0p1 * 2048 124735487 124733440 59.5G b W95 FAT32
michael at laptop:~$ sudo fsck -N /dev/mmcblk0p1
> fsck from util-linux 2.39.3
> [/usr/sbin/fsck.vfat (1) -- /dev/mmcblk0p1] fsck.vfat /dev/mmcblk0p1
michael at laptop:~$ sudo file -s /dev/mmcblk0p1
> /dev/mmcblk0p1: DOS/MBR boot sector, code offset 0x58+2, OEM-ID
> "mkfs.fat", sectors/cluster 64, reserved sectors 64, Media descriptor 0xf8,
> sectors/track 16, heads 4, hidden sectors 2048, sectors 124733440 (volumes
> > 32 MB), FAT (32 bit), sectors/FAT 15232, reserved 0x1, serial number
> 0x3e21a96, unlabeled
michael at laptop:~$ sudo ls -l /mnt/sdcard/
> total 864
> -rw-r--r-- 1 michael michael 78728 Oct 21 23:29 bcm2712-rpi-5-b.dtb
> -rw-r--r-- 1 michael michael 67 Oct 23 18:05 config.txt
> -rw-r--r-- 1 michael michael 701248 Oct 23 18:05 u-boot.bin
I also updated my config.txt to only include the two lines you mentioned,
and am getting the same output as before (which is probably expected just
from that change).
On Thu, Oct 23, 2025 at 8:02 PM Peter Robinson <pbrobinson at gmail.com> wrote:
> Hi Mikeyy,
>
> > I'm trying to set up U-Boot as a bootloader on my Raspberry Pi 5 for
> custom
> > kernel development. For some reason though, I don't ever get to the
> U-Boot
> > environment at the end where I can type and input commands. It seemingly
> > gets stuck after BL31 (which I believe is the Arm Trusted Firmware). Any
> > help would be greatly appreciated.
> >
> > Setup:
> >
> > - U-Boot version: v2025.10
> > - Built with: make CROSS_COMPILE=aarch64-linux-gnu-
> rpi_arm64_defconfig
> > - Connection: Using the dedicated 3-pin debug UART header with
> > USB-to-serial adapter
> > - SD card has: u-boot.bin, bcm2712-rpi-5-b.dtb, and config.txt
>
> What sort of partition/filesystem do you have?
>
> > This is my specific adapter:
> >
> https://www.amazon.com.au/Debugger-Raspberry-Connector-Debugging-Transmission/dp/B0CZP8DZK8
> > which I plug into my laptop, and run the command: *sudo minicom -D
> > /dev/ttyACM0 -b 115200*. I am specifically using the dedicated 3-pin UART
> > header which is new on the Rpi5.
> >
> > My config.txt is
> >
> > > arm_64bit=1
> > > kernel=u-boot.bin
>
> The above should be enough, the device should pass the right DT from
> the earlier firmware. What is
>
> > > device_tree=bcm2712-rpi-5-b.dtb
> > > os_check=0
> > > # Enable UART0
> > > enable_uart=1
> > > core_freq_min=500
> >
> >
> >
> > Here is my output after connecting to minicom:
> >
> > Welcome to minicom 2.9
> > > OPTIONS: I18n
> > > Port /dev/ttyACM0, 00:28:12
> > > Press CTRL-A Z for help on special keys
> > > 1.02 RPi: BOOTSYS release VERSION:5855b10b DATE: 2025/06/13 TIME:
> > > 10:39:26
> > > 1.02 BOOTMODE: 0x06 partition 0 build-ts BUILD_TIMESTAMP=1749807566
> > > serial 0d57824f boardrev c049
> > > 1.03 AON_RESET: 00000003 PM_RSTS 00001000
> > > 1.04 POWER_OFF_ON_HALT: 0 WAIT_FOR_POWER_BUTTON 0 power-on-reset 1
> > > 1.05 RP1_BOOT chip ID: 0x20001927
> > > 1.05 PCIEx1: PWR 0 DET_WAKE 0
> > > 1.05 part 00000000 reset_info 00000000
> > > 1.06 PMIC reset-event 00000000 rtc 00000001 alarm 00000000 enabled 0
> > > 1.06 uSD voltage 3.3V
> > > 1.07 SDRAM_CONFIG: 15
> > > 1.07 Initialising SDRAM rank 2 total-size: 32 Gbit 4267 (0x15 0x15)
> > > 1.08 DDR 4267 1 0 32 152 BL:1
> > > 2.94 OTP boardrev c04171 bootrom a a
> > > 2.94 Customer key hash
> > > 0000000000000000000000000000000000000000000000000000000000000000
> > > 2.95 VC-JTAG unlocked
> > > 2.97 RP1_BOOT chip ID: 0x20001927
> > > 3.61 RP1_BOOT chip ID: 0x20001927
> > > 3.61 RP1_BOOT: fw size 46888
> > > 4.25 PCI2 init
> > > 4.25 PCI2 reset
> > > 4.30 PCIe scan 00001de4:00000001
> > > 4.30 RP1_CHIP_INFO 20001927
> > > 4.30 RPi: BOOTLOADER release VERSION:5855b10b DATE: 2025/06/13 TIME:
> > > 10:39:26
> > > 4.31 BOOTMODE: 0x06 partition 0 build-ts BUILD_TIMESTAMP=1749807566
> > > serial 0d57824f boardrev c045
> > > 4.32 PCIEx1: PWR 0 DET_WAKE 0
> > > 4.24 M.2 PCIe HAT not detected.
> > > 4.34 usb_pd_init status 3
> > > 4.34 USB_PD CONFIG 0 41
> > > 4.42 XHCI-STOP
> > > 4.42 xHC0 ver: 272 HCS: 03000440 140000f1 07ff000a HCC: 0240fe6d
> > > 4.43 USBSTS 1
> > > 4.43 xHC0 ver: 272 HCS: 03000440 140000f1 07ff000a HCC: 0240fe6d
> > > 4.43 xHC0 ports 3 slots 64 intrs 4
> > > 4.45 XHCI-STOP
> > > 4.45 xHC1 ver: 272 HCS: 03000440 140000f1 07ff000a HCC: 0240fe6d
> > > 4.45 USBSTS 1
> > > 4.45 xHC1 ver: 272 HCS: 03000440 140000f1 07ff000a HCC: 0240fe6d
> > > 4.46 xHC1 ports 3 slots 64 intrs 4
> > > 4.47 USB-PD: src-cap PDO object1 0x0a01912c
> > > 4.47 Current 3000 mA
> > > 4.47 Voltage 5000 mV
> > > 4.47 USB-PD: src-cap PDO object2 0x0002d12c
> > > 4.48 Current 3000 mA
> > > 4.48 Voltage 9000 mV
> > > 4.48 USB-PD: src-cap PDO object3 0x0004b12c
> > > 4.48 Current 3000 mA
> > > 4.49 Voltage 15000 mV
> > > 4.49 USB-PD: src-cap PDO object4 0x00064145
> > > 4.49 Current 3250 mA
> > > 4.49 Voltage 20000 mV
> > > 4.50 USB-PD: src-cap PDO object5 0xc0dc323c
> > > 4.50 USB-PD: src-cap PDO object6 0xc1a4323c
> > > 4.10 Boot mode: SD (01) order f4
> > > 9.17 SD HOST: 200000000 CTL0: 0x00800000 BUS: 400000 Hz actual:
> 390625
> > > HZ div: 512 (256) status:6
> > > 9.18 SD HOST: 200000000 CTL0: 0x00800f00 BUS: 400000 Hz actual:
> 390625
> > > HZ div: 512 (256) status:6
> > > 9.40 OCR c0ff8000 [340]
> > > CID: 00035344534e363447856a498e400198
> > > CSD: 400e0032db790001dbd37f800a404000
> > > 9.41 SD: bus-width: 4 spec: 2 SCR: 0x02458487 0x00000000
> > > 9.42 SD HOST: 200000000 CTL0: 0x00800f04 BUS: 50000000 Hz actual:
> > > 50000000 HZ div: 4 (2) status:2
> > > 9.43 MBR: 0x00000800,124733440 type: 0x0b
> > > 9.43 MBR: 0x00000000, 0 type: 0x00
> > > 9.43 MBR: 0x00000000, 0 type: 0x00
> > > 9.44 MBR: 0x00000000, 0 type: 0x00
> > > 9.46 Trying partition: 0
> > > 9.92 type: 32 lba: 2048 'mkfs.fat' ' NO NAME ' clusters 1948483
> (64)
> > > 9.49 rsc 64 fat-sectors 15232 root dir cluster 2 sectors 0 entries 0
> > > 9.50 FAT32 clusters 1948483
> > > 9.50 [sdcard] autoboot.txt not found
> > > 9.50 Select partition rsts 0 C(boot_partition) 0 EEPROM config 0
> result 1
> > > 9.15 Trying partition: 1
> > > 9.17 type: 32 lba: 2048 'mkfs.fat' ' NO NAME ' clusters 1948483
> (64)
> > > 9.52 rsc 64 fat-sectors 15232 root dir cluster 2 sectors 0 entries 0
> > > 9.53 FAT32 clusters 1948483
> > > 9.40 Read config.txt bytes 122 hnd 0x76
> > > 9.54 [sdcard] pieeprom.upd not found
> > > 9.45 usb_max_current_enable default 0 max-current 3000
> > > 9.55 Selecting USB low current limit
> > > 9.55 MESS:00:00:09.557951:0: *** Restart logging
> > > 9.62 Read /config.txt bytes 122 hnd 0x76
> > > 9.66 Read /config.txt bytes 122 hnd 0x76
> > > 9.57 MESS:00:00:09.571810:0: Initial voltage 800000 temp 30136
> > > 9.77 MESS:00:00:09.772217:0: avs_2712: AVS pred 9012 901200 temp
> 30136
> > > 9.77 MESS:00:00:09.775819:0: vpred 901 mV +0
> > > 9.78 MESS:00:00:09.784492:0: FB framebuffer_swap 1
> > > 9.78 MESS:00:00:09.786357:0: Select resolution HDMI0/2 hotplug 0
> > > max_mode 2
> > > 9.79 MESS:00:00:09.793247:0: Select resolution HDMI1/2 hotplug 0
> > > max_mode 2
> > > 9.80 Loading 'bcm2712-rpi-5-b.dtb' to 0x00000000 offset 0x100
> > > 9.15 Read bcm2712-rpi-5-b.dtb bytes 78728 hnd 0x3c
> > > 9.37 /overlays/overlay_map.dtb
> > > 9.38 /overlays/bcm2712d0.dtbo
> > > 9.86 PCIEx1: PWR 0 DET_WAKE 0
> > > 9.80 Read /config.txt bytes 122 hnd 0x76
> > > 9.94 [sdcard] /cmdline.txt not found
> > > 9.44 /cmdline.txt
> > > 9.94 MESS:00:00:09.946696:0: Failed to open command line file
> > > 'cmdline.txt'
> > > 10.13 MESS:00:00:10.131602:0: RPM 0, max RPM 0
> > > 10.16 BMD "armstub8-2712.bin" not found
> > > 10.63 fs_open: 'armstub8-2712.bin'
> > > 10.16 Loading 'u-boot.bin' to 0x00000000 offset 0x200000
> > > 10.04 Read u-boot.bin bytes 700232 hnd 0x5b
>
> It seems to find it on disk and load it OK.
>
> > > 10.20 MESS:00:00:10.206013:0: Kernel relocated to 0x80000
> > > 10.21 MESS:00:00:10.210874:0: Device tree loaded to 0x2efec600 (size
> > > 0x13957)
> > > 10.21 PCI1 reset
> > > 10.22 PCI2 reset
> > > 10.23 set_reboot_order 0
> > > 10.23 set_reboot_arg1 0
> > > 10.24 USB-OTG disconnect
> > > 10.28 MESS:00:00:10.283221:0: BSC_A no ACK
> > > 10.28 MESS:00:00:10.284454:0: BSC_A no ACK
> > > 10.28 MESS:00:00:10.288380:0: BSC_A no ACK
> > > 10.31 MESS:00:00:10.312311:0: BSC_B no ACK
> > > 10.31 MESS:00:00:10.313538:0: BSC_B no ACK
> > > 10.31 MESS:00:00:10.317473:0: BSC_B no ACK
> > > 10.34 MESS:00:00:10.341242:0: Starting OS 10341 ms
> > > 10.34 MESS:00:00:10.346852:0: 00000040: -> 00000480
> > > 10.34 MESS:00:00:10.348705:0: 00000030: -> 00100080
> > > 10.35 MESS:00:00:10.353418:0: 00000034: -> 00100080
> > > 10.35 MESS:00:00:10.358131:0: 00000038: -> 00100080
> > > 10.36 MESS:00:00:10.362844:0: 0000003c: -> 00100080
> > > NOTICE: BL31: v2.6(release):v2.6-240-gfc45bc492
> > > NOTICE: BL31: Built : 12:55:13, Dec 4 2024
>
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