u-boot/linux hangs after "Starting Linux...."

I need some pointers on how to debug this further. My setup looks like this: * Hardware: CM3 * Pi Firmware boots u-boot, u-boot loads FIT image and is supposed to boot it. * FIT image contains the kernel (uncompressed, ~7MB), device-tree, ramdisk (~2.5MB) * Kernel is 5.15, u-boot is 2022.01 The FIT image loads and verifies fine, my bootargs are set and from what I can tell, all should be valid. The issue happened after updating the kernel from 4.19 to 5.15 (via a Yocto update, image size increased roughly 3 MB). I tried enabling earlyprintk, but that either did nothing or we don't even come far enough for that. Relevant part of the boot script (there's some bunch of hopefully unrelated stuff in there):

load mmc 0:2 $ramdisk_addr_r "/boot"$kernel_image


# "ramdisk_addr_r" is 0x02700000
# "fit_conf" is #conf-bcm2710-rpi-cm3.dtb#conf-overlays_i2c-ds1307.dtbo#conf-overlays_audio-on.dtbo#conf-overlays_gpio43-reset.dtbo#conf-overlays_mmc-non-removable.dtbo#conf-overlays_spi.dtbo
bootm "${ramdisk_addr_r}${fit_conf}"

Boot arguments (some very likely unrelated stuff stripped):

console=ttyAMA0,115200 earlyprintk 8250.nr_uarts=1 bcm2708_fb.fbwidth=480 bcm2708_fb.fbheight=800 bcm2708_fb.fbswap=1 dwc_otg.lpm_enable=0 usbhid.mousepoll=0 vc_mem.mem_base=0x3ec00000 vc_mem.mem_size=0x40000000 cma=512M fbcon=vc:2-4 logo.nologo video=HDMI-A-1:480x800MR-24@60 dwc_otg.microframe_schedule=1 smsc95xx.turbo_mode=N root=/dev/ram0 rw rootwait rootdelay=2 ramdisk_size=8192 panic=10

The log with all debugging options I could find (first part is rpi firmware):

Raspberry Pi Bootcode

Found SD card, config.txt = 1, start.elf = 1, recovery.elf = 0, timeout = 0
Read File: config.txt, 36655 (bytes)




Raspberry Pi Bootcode
Read File: config.txt, 36655
Read File: start.elf, 2973536 (bytes)
Read File: fixup.dat, 7262 (bytes)
MESS:00:00:03.766632:0: brfs: File read: /mfs/sd/config.txt
MESS:00:00:03.790677:0: brfs: File read: 36655 bytes
MESS:00:00:03.824492:0: brfs: File read: /mfs/sd/edid.dat
MESS:00:00:03.828906:0: brfs: File read: 128 bytes
MESS:00:00:03.833665:0: brfs: File read: /mfs/sd/config.txt
MESS:00:00:03.838028:0: gpioman: gpioman_get_pin_num: pin FLASH_0_ENABLE not defined
MESS:00:00:03.845480:0: gpioman: gpioman_get_pin_num: pin FLASH_0_INDICATOR not defined
piSS:00:00:03.853227:0: gpioman: gpioman_get_pin_num: pin FMISEPLSAYS_S:0D0:A00 :0n3.o85t82 98d:0e: fgpiionmaen:d g
_goman
  MEeSSt:0_0:p00i:0n3._86n43u16m:0::  gppioimann:  gFpiLomAanSH__0g_IeNDtIC_ATpORi nnot_ dnefuMm:E pSinS L:ED0S_0PW:R_0OK0 n:ot0 d3ef.in8ed7
2n2ed1
9:0: gpioman: gpioman_get_pin_num: pin LEDS_PWR_OK not defined
MESS:00:00:03.896414:0: gpioman: gpioman_get_pin_num: pin BT_ON not defined
MESS:00:00:03.901684:0: gpioman: gpioman_get_pin_num: pin WL_ON not defined
MESS:00:00:03.935160:0: gpioman: gpioman_get_pin_num: pin LEDS_PWR_OK not defined
MESS:00:00:03.940993:0: *** Restart logging
MESS:00:00:03.944864:0: brfs: File read: 36655 bytes
MESS:00:00:03.970043:0: HDMI0: hdmi_pixel_encoding: 162000000
MESS:00:00:03.974816:0: gpioman: gpioman_get_pin_num: pin CAMERA_0_I2C_PORT not defined
MESS:00:00:03.981831:0: dtb_file 'bcm2710-rpi-cm3.dtb'
MESS:00:00:03.990825:0: brfs: File read: /mfs/sd/bcm2710-rpi-cm3.dtb
MESS:00:00:03.995486:0: Loaded 'bcm2710-rpi-cm3.dtb' to 0x100 size 0x75b2
MESS:00:00:04.015999:0: brfs: File read: 30130 bytes
MESS:00:00:04.096779:0: brfs: File read: /mfs/sd/config.txt
MESS:00:00:04.123208:0: dtparam: i2c1=on
MESS:00:00:04.134136:0: dtparam: i2c_arm=on
MESS:00:00:04.145334:0: brfs: File read: 36655 bytes
MESS:00:00:04.148795:0: Failed to load overlay 'vc4-kms-v3d'
MESS:00:00:04.154137:0: dtparam: audio=on
MESS:00:00:04.168070:0: brfs: File read: /mfs/sd/overlays/vc4-kms-v3d.dtbo
MESS:00:00:04.179270:0: brfs: File read: /mfs/sd/cmdline.txt
MESS:00:00:04.183258:0: Read command line from file 'cmdline.txt':
MESS:00:00:04.189134:0: 'dwc_otg.lpm_enable=0 console=serial0,115200 root=/dev/mmcblk0p2 rootfstype=ext4 rootwait'
MESS:00:00:04.973468:0: gpioman: gpioman_get_pin_num: pin WL_ON not defined
MESS:00:00:04.987033:0: brfs: File read: 89 bytes
MESS:00:00:05.038864:0: brfs: File read: /mfs/sd/kernel7.img
MESS:00:00:05.042831:0: Loaded 'kernel7.img' to 0x8000 size 0x85f1c
MESS:00:00:05.048833:0: Device tree loaded to 0x2eff8400 (size 0x7b09)
MESS:00:00:05.056422:0: uart: Set PL011 baud rate to 103448.300000 Hz
MESS:00:00:05.062784:0: uart: Baud rate change done...
MESS:00:00:05.066216:0: uart: Baud rate change done...
MESS:00:00:05.073531:0: gpioman: gpioman_get_pin_num: pin SDCARD_CONTROL_POWER not defined


U-Boot 2022.01 (Jan 01 2000 - 00:00:00 +0000)

DRAM:  960 MiB
RPI Compute Module 3+ (0xa02100)
MMC:   mmc@7e202000: 0
Loading Environment from FAT... WARNING at drivers/mmc/bcm2835_sdhost.c:414/bcm2835_send_command()!
WARNING at drivers/mmc/bcm2835_sdhost.c:414/bcm2835_send_command()!
Unable to read "uboot.env" from mmc0:1... 
In:    serial
Out:   vidconsole
Err:   vidconsole
Net:   No ethernet found.
Hit any key to stop autoboot:  0
WARNING at drivers/mmc/bcm2835_sdhost.c:414/bcm2835_send_command()!
WARNING at drivers/mmc/bcm2835_sdhost.c:414/bcm2835_send_command()!
switch to partitions #0, OK
mmc0(part 0) is current device
Scanning mmc 0:1...
Found U-Boot script /boot.scr
177 bytes read in 1 ms (172.9 KiB/s)
## Executing script at 02400000
1551 bytes read in 1 ms (1.5 MiB/s)
Saving Environment to FAT... OK
669 bytes read in 1 ms (653.3 KiB/s)
ostree_root=/ostree/boot.1/poky/2b3c8673ae53eb1a02210e627c06ac617b0e758fbf71afa0c7e91a8ff5931aeb/0
215 bytes read in 5 ms (42 KiB/s)
9269132 bytes read in 387 ms (22.8 MiB/s)
## Loading kernel from FIT Image at 02700000 ...
   Using 'conf-bcm2710-rpi-cm3.dtb' configuration
   Trying 'kernel-1' kernel subimage
     Description:  Linux kernel
     Type:         Kernel Image
     Compression:  uncompressed
     Data Start:   0x02700110
     Data Size:    6631488 Bytes = 6.3 MiB
     Architecture: ARM
     OS:           Linux
     Load Address: 0x00008000
     Entry Point:  0x00080000
     Hash algo:    sha256
     Hash value:   6ff211d7430e5179b546ad46e3783fbe797e036302c9d55a0adaf09b03a7ad40
   Verifying Hash Integrity ... sha256+ OK
## Loading ramdisk from FIT Image at 02700000 ...
   Using 'conf-bcm2710-rpi-cm3.dtb' configuration
   Trying 'ramdisk-1' ramdisk subimage
     Description:  initramfs-ostree-image
     Type:         RAMDisk Image
     Compression:  uncompressed
     Data Start:   0x02d5be80
     Data Size:    2599324 Bytes = 2.5 MiB
     Architecture: ARM
     OS:           Linux
     Load Address: unavailable
     Entry Point:  unavailable
     Hash algo:    sha256
     Hash value:   f10f8afa25b5416fdf6f2790c087661999c5502260ec8e2e3caff5d9d9a48632
   Verifying Hash Integrity ... sha256+ OK
## Loading fdt from FIT Image at 02700000 ...
   Using 'conf-bcm2710-rpi-cm3.dtb' configuration
   Trying 'fdt-bcm2710-rpi-cm3.dtb' fdt subimage
     Description:  Flattened Device Tree blob
     Type:         Flat Device Tree
     Compression:  uncompressed
     Data Start:   0x02d53260
     Data Size:    30130 Bytes = 29.4 KiB
     Architecture: ARM
     Load Address: 0x05000000
     Hash algo:    sha256
     Hash value:   50c601276d58a4a1daded000c4d8a7a5ef917436a9e483675ff8e93265d6c294
   Verifying Hash Integrity ... sha256+ OK
   Loading fdt from 0x02d53260 to 0x05000000
## Loading fdt from FIT Image at 02700000 ...
   Using 'conf-overlays_i2c-ds1307.dtbo' configuration
   Trying 'fdt-overlays_i2c-ds1307.dtbo' fdt subimage
     Description:  Flattened Device Tree blob
     Type:         Flat Device Tree
     Compression:  uncompressed
     Data Start:   0x02d5a908
     Data Size:    508 Bytes = 508 Bytes
     Architecture: ARM
     Load Address: 0x06000000
     Hash algo:    sha256
     Hash value:   2efdf54d40f36118a2f771de7b412bcdcb56819bfd646719a429b1580a9b67bd
   Verifying Hash Integrity ... sha256+ OK
## Loading fdt from FIT Image at 02700000 ...
   Using 'conf-overlays_audio-on.dtbo' configuration
   Trying 'fdt-overlays_audio-on.dtbo' fdt subimage
     Description:  Flattened Device Tree blob
     Type:         Flat Device Tree
     Compression:  uncompressed
     Data Start:   0x02d5abf4
     Data Size:    263 Bytes = 263 Bytes
     Architecture: ARM
     Load Address: 0x06000000
     Hash algo:    sha256
     Hash value:   c5dfd7893d0248f2c966995fe332cdb075771d398326c0c997e43120c793b818
   Verifying Hash Integrity ... sha256+ OK
## Loading fdt from FIT Image at 02700000 ...
   Using 'conf-overlays_gpio43-reset.dtbo' configuration
   Trying 'fdt-overlays_gpio43-reset.dtbo' fdt subimage
     Description:  Flattened Device Tree blob
     Type:         Flat Device Tree
     Compression:  uncompressed
     Data Start:   0x02d5adf0
     Data Size:    1340 Bytes = 1.3 KiB
     Architecture: ARM
     Load Address: 0x06000000
     Hash algo:    sha256
     Hash value:   c9fc421b77391ae8323147007cef422c1c80246aa8606927a93fe1ecb122fdbd
   Verifying Hash Integrity ... sha256+ OK
## Loading fdt from FIT Image at 02700000 ...
   Using 'conf-overlays_mmc-non-removable.dtbo' configuration
   Trying 'fdt-overlays_mmc-non-removable.dtbo' fdt subimage
     Description:  Flattened Device Tree blob
     Type:         Flat Device Tree
     Compression:  uncompressed
     Data Start:   0x02d5b424
     Data Size:    263 Bytes = 263 Bytes
     Architecture: ARM
     Load Address: 0x06000000
     Hash algo:    sha256
     Hash value:   06a9b23fac0a5d75e671107fcecbf556ababc4d4fe25218ba47d1803024aa751
   Verifying Hash Integrity ... sha256+ OK
## Loading fdt from FIT Image at 02700000 ...
   Using 'conf-overlays_spi.dtbo' configuration
   Trying 'fdt-overlays_spi.dtbo' fdt subimage
     Description:  Flattened Device Tree blob
     Type:         Flat Device Tree
     Compression:  uncompressed
     Data Start:   0x02d5b618
     Data Size:    1930 Bytes = 1.9 KiB
     Architecture: ARM
     Load Address: 0x06000000
     Hash algo:    sha256
     Hash value:   024bf878c83abe13ecb49273611177a1b72f0975377a34ad077977f023c1bb79
   Verifying Hash Integrity ... sha256+ OK
   Booting using the fdt blob at 0x5000000
   Loading Kernel Image
   Using Device Tree in place at 05000000, end 0500ad04

Starting kernel ...

How can I find out what's blocking my boot?