PROCESSOR-SDK-AM335X: No console on beaglebone if I enable uart5

Running linux-6.1 from the processor SDK version 09.01.00.001, the serial console becomes inoperative if I enable uart5 on the device tree.

I followed the Release Notes for AM335X and created a demo build from poky (kirkstone) and meta-ti-bsp, then I set MACHINE to "am335x-evm".

If I build a core-image-minimal from the stock kernel, it boots fine and I get a working serial console when boot is complete:

The editor apparently doesn't like me embedding the bellow snippet into a code block so apologies for placing it inline.

------------8<-------------------------

U-Boot SPL 2023.04-gd74d0993e2 (Oct 18 2023 - 17:49:46 +0000)
Trying to boot from MMC1

U-Boot 2023.04-gd74d0993e2 (Oct 18 2023 - 17:49:46 +0000)

CPU : AM335X-GP rev 2.1
Model: TI AM335x BeagleBone Black
DRAM: 512 MiB
Core: 160 devices, 18 uclasses, devicetree: separate
WDT: Started wdt@44e35000 with servicing every 1000ms (60s timeout)
NAND: 0 MiB
MMC: OMAP SD/MMC: 0, OMAP SD/MMC: 1
Loading Environment from FAT... Unable to read "uboot.env" from mmc0:1...
<ethaddr> not set. Validating first E-fuse MAC
Net: eth2: ethernet@4a100000, eth3: usb_ether
Hit any key to stop autoboot: 0
switch to partitions #0, OK
mmc0 is current device
Scanning mmc 0:1...
Found /extlinux/extlinux.conf
Retrieving file: /extlinux/extlinux.conf
1: Poky (Yocto Project Reference Distro)
Retrieving file: /extlinux/../zImage
append: root=PARTUUID=fff741b0-02 rootwait rw earlycon console=ttyO0,115200n8,115200
Retrieving file: /extlinux/../am335x-boneblack.dtb
Kernel image @ 0x82000000 [ 0x000000 - 0x74b200 ]
## Flattened Device Tree blob at 88000000
Booting using the fdt blob at 0x88000000
Working FDT set to 88000000
Loading Device Tree to 8ffe5000, end 8ffffed3 ... OK
Working FDT set to 8ffe5000

Starting kernel ...

[ 0.000000] Booting Linux on physical CPU 0x0
[ 0.000000] Linux version 6.1.46-g1d4b5da681 (oe-user@oe-host) (arm-poky-linux-gnueabi-gcc (GCC) 11.4.0, GNU ld (GNU Binutils) 2.38.20220708) #1 PREEMPT Thu Oct 19 10:19:08 UTC 2023
[ 0.000000] CPU: ARMv7 Processor [413fc082] revision 2 (ARMv7), cr=10c5387d
[ 0.000000] CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
[ 0.000000] OF: fdt: Machine model: TI AM335x BeagleBone Black
[ 0.000000] earlycon: omap8250 at MMIO 0x44e09000 (options '')
[ 0.000000] printk: bootconsole [omap8250] enabled
[ 0.000000] Memory policy: Data cache writeback
[ 0.000000] efi: UEFI not found.
[ 0.000000] cma: Reserved 64 MiB at 0x9b800000
[ 0.000000] Zone ranges:
[ 0.000000] Normal [mem 0x0000000080000000-0x000000009fdfffff]
[ 0.000000] HighMem empty
[ 0.000000] Movable zone start for each node
[ 0.000000] Early memory node ranges
[ 0.000000] node 0: [mem 0x0000000080000000-0x000000009fdfffff]
[ 0.000000] Initmem setup node 0 [mem 0x0000000080000000-0x000000009fdfffff]
[ 0.000000] CPU: All CPU(s) started in SVC mode.
[ 0.000000] AM335X ES2.1 (sgx neon)
[ 0.000000] Built 1 zonelists, mobility grouping on. Total pages: 129540
[ 0.000000] Kernel command line: root=PARTUUID=fff741b0-02 rootwait rw earlycon console=ttyO0,115200n8,115200
[ 0.000000] Dentry cache hash table entries: 65536 (order: 6, 262144 bytes, linear)
[ 0.000000] Inode-cache hash table entries: 32768 (order: 5, 131072 bytes, linear)
[ 0.000000] mem auto-init: stack:off, heap alloc:off, heap free:off
[ 0.000000] Memory: 433560K/522240K available (11264K kernel code, 1470K rwdata, 3264K rodata, 1024K init, 287K bss, 23144K reserved, 65536K cma-reserved, 0K highmem)
[ 0.000000] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
[ 0.000000] trace event string verifier disabled
[ 0.000000] rcu: Preemptible hierarchical RCU implementation.
[ 0.000000] rcu: RCU event tracing is enabled.
[ 0.000000] Trampoline variant of Tasks RCU enabled.
[ 0.000000] rcu: RCU calculated value of scheduler-enlistment delay is 10 jiffies.
[ 0.000000] NR_IRQS: 16, nr_irqs: 16, preallocated irqs: 16
[ 0.000000] IRQ: Found an INTC at 0x(ptrval) (revision 5.0) with 128 interrupts
[ 0.000000] rcu: srcu_init: Setting srcu_struct sizes based on contention.
[ 0.000000] TI gptimer clocksource: always-on /ocp/interconnect@44c00000/segment@200000/target-module@31000
[ 0.000002] sched_clock: 32 bits at 24MHz, resolution 41ns, wraps every 89478484971ns
[ 0.008062] clocksource: dmtimer: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 79635851949 ns
[ 0.018037] TI gptimer clockevent: 24000000 Hz at /ocp/interconnect@48000000/segment@0/target-module@40000
[ 0.029725] Console: colour dummy device 80x30
[ 0.034332] WARNING: Your 'console=ttyO0' has been replaced by 'ttyS0'
[ 0.041116] This ensures that you still see kernel messages. Please
[ 0.047559] update your kernel commandline.
[ 0.051891] Calibrating delay loop... 996.14 BogoMIPS (lpj=4980736)
[ 0.094481] CPU: Testing write buffer coherency: ok
[ 0.099567] CPU0: Spectre v2: using BPIALL workaround
[ 0.104758] pid_max: default: 32768 minimum: 301
[ 0.109688] Mount-cache hash table entries: 1024 (order: 0, 4096 bytes, linear)
[ 0.117211] Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes, linear)
[ 0.126752] cblist_init_generic: Setting adjustable number of callback queues.
[ 0.134259] cblist_init_generic: Setting shift to 0 and lim to 1.
[ 0.140696] Setting up static identity map for 0x80100000 - 0x80100060
[ 0.147563] rcu: Hierarchical SRCU implementation.
[ 0.152514] rcu: Max phase no-delay instances is 1000.
[ 0.159603] EFI services will not be available.
[ 0.164859] devtmpfs: initialized
[ 0.182965] VFP support v0.3: implementor 41 architecture 3 part 30 variant c rev 3
[ 0.191204] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns
[ 0.201352] futex hash table entries: 256 (order: -1, 3072 bytes, linear)
[ 0.213379] pinctrl core: initialized pinctrl subsystem
[ 0.219910] DMI not present or invalid.
[ 0.224517] NET: Registered PF_NETLINK/PF_ROUTE protocol family
[ 0.232917] DMA: preallocated 256 KiB pool for atomic coherent allocations
[ 0.241223] thermal_sys: Registered thermal governor 'step_wise'
[ 0.241327] cpuidle: using governor menu
[ 0.266464] No ATAGs?
[ 0.268900] hw-breakpoint: debug architecture 0x4 unsupported.
[ 0.276928] Serial: AMBA PL011 UART driver
[ 0.310455] SCSI subsystem initialized
[ 0.314984] usbcore: registered new interface driver usbfs
[ 0.328092] usbcore: registered new interface driver hub
[ 0.333596] usbcore: registered new device driver usb
[ 0.348485] pps_core: LinuxPPS API ver. 1 registered
[ 0.353596] pps_core: Software ver. 5.3.6 - Copyright 2005-2007 Rodolfo Giometti <giometti@linux.it>
[ 0.378064] PTP clock support registered
[ 0.382279] EDAC MC: Ver: 3.0.0
[ 0.400134] clocksource: Switched to clocksource dmtimer
[ 0.425541] NET: Registered PF_INET protocol family
[ 0.430965] IP idents hash table entries: 8192 (order: 4, 65536 bytes, linear)
[ 0.450683] tcp_listen_portaddr_hash hash table entries: 1024 (order: 0, 4096 bytes, linear)
[ 0.459401] Table-perturb hash table entries: 65536 (order: 6, 262144 bytes, linear)
[ 0.490145] TCP established hash table entries: 4096 (order: 2, 16384 bytes, linear)
[ 0.498147] TCP bind hash table entries: 4096 (order: 3, 32768 bytes, linear)
[ 0.520181] TCP: Hash tables configured (established 4096 bind 4096)
[ 0.526824] UDP hash table entries: 256 (order: 0, 4096 bytes, linear)
[ 0.540147] UDP-Lite hash table entries: 256 (order: 0, 4096 bytes, linear)
[ 0.547470] NET: Registered PF_UNIX/PF_LOCAL protocol family
[ 0.570620] RPC: Registered named UNIX socket transport module.
[ 0.576721] RPC: Registered udp transport module.
[ 0.590142] RPC: Registered tcp transport module.
[ 0.594980] RPC: Registered tcp NFSv4.1 backchannel transport module.
[ 0.610143] PCI: CLS 0 bytes, default 64
[ 0.621505] Initialise system trusted keyrings
[ 0.640296] workingset: timestamp_bits=30 max_order=17 bucket_order=0
[ 0.662457] squashfs: version 4.0 (2009/01/31) Phillip Lougher
[ 0.680501] NFS: Registering the id_resolver key type
[ 0.685760] Key type id_resolver registered
[ 0.690060] Key type id_legacy registered
[ 0.700314] nfs4filelayout_init: NFSv4 File Layout Driver Registering...
[ 0.707218] nfs4flexfilelayout_init: NFSv4 Flexfile Layout Driver Registering...
[ 0.730175] ntfs: driver 2.1.32 [Flags: R/O].
[ 0.735231] Key type asymmetric registered
[ 0.739451] Asymmetric key parser 'x509' registered
[ 0.760324] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 247)
[ 0.767940] io scheduler mq-deadline registered
[ 0.780149] io scheduler kyber registered
[ 0.885941] Serial: 8250/16550 driver, 5 ports, IRQ sharing enabled
[ 0.894889] STMicroelectronics ASC driver initialized
[ 0.931831] brd: module loaded
[ 0.945612] loop: module loaded
[ 0.964588] CAN device driver interface
[ 0.968915] e1000e: Intel(R) PRO/1000 Network Driver
[ 0.990139] e1000e: Copyright(c) 1999 - 2015 Intel Corporation.
[ 0.996334] igb: Intel(R) Gigabit Ethernet Network Driver
[ 1.010136] igb: Copyright (c) 2007-2014 Intel Corporation.
[ 1.016701] pegasus: Pegasus/Pegasus II USB Ethernet driver
[ 1.030198] usbcore: registered new interface driver pegasus
[ 1.036070] usbcore: registered new interface driver asix
[ 1.060180] usbcore: registered new interface driver ax88179_178a
[ 1.066478] usbcore: registered new interface driver cdc_ether
[ 1.080184] usbcore: registered new interface driver smsc75xx
[ 1.086131] usbcore: registered new interface driver smsc95xx
[ 1.110181] usbcore: registered new interface driver net1080
[ 1.116029] usbcore: registered new interface driver cdc_subset
[ 1.130190] usbcore: registered new interface driver zaurus
[ 1.135989] usbcore: registered new interface driver cdc_ncm
[ 1.150874] usbcore: registered new interface driver usb-storage
[ 1.170642] i2c_dev: i2c /dev entries driver
[ 1.177087] cpuidle: enable-method property 'ti,am3352' found operations
[ 1.200816] sdhci: Secure Digital Host Controller Interface driver
[ 1.207185] sdhci: Copyright(c) Pierre Ossman
[ 1.220379] Synopsys Designware Multimedia Card Interface Driver
[ 1.226711] sdhci-pltfm: SDHCI platform and OF driver helper
[ 1.240661] ledtrig-cpu: registered to indicate activity on CPUs
[ 1.247248] usbcore: registered new interface driver usbhid
[ 1.270134] usbhid: USB HID core driver
[ 1.276676] NET: Registered PF_INET6 protocol family
[ 1.301076] Segment Routing with IPv6
[ 1.304917] In-situ OAM (IOAM) with IPv6
[ 1.309038] sit: IPv6, IPv4 and MPLS over IPv4 tunneling driver
[ 1.320953] NET: Registered PF_PACKET protocol family
[ 1.326163] can: controller area network core
[ 1.350213] NET: Registered PF_CAN protocol family
[ 1.355147] can: raw protocol
[ 1.358200] can: broadcast manager protocol
[ 1.370146] can: netlink gateway - max_hops=1
[ 1.375035] Key type dns_resolver registered
[ 1.379571] ThumbEE CPU extension supported.
[ 1.400153] Registering SWP/SWPB emulation handler
[ 1.405571] omap_voltage_late_init: Voltage driver support not added
[ 1.421071] Loading compiled-in X.509 certificates
[ 1.500721] pinctrl-single 44e10800.pinmux: 142 pins, size 568
[ 1.521728] ti-sysc: probe of 44e31000.target-module failed with error -16
[ 1.561473] ti-sysc: probe of 48040000.target-module failed with error -16
[ 1.602047] gpio gpiochip0: (gpio-0-31): not an immutable chip, please consider fixing it!
[ 1.620506] OMAP GPIO hardware version 0.1
[ 1.648597] at24 2-0054: supply vcc not found, using dummy regulator
[ 1.694230] at24 2-0055: supply vcc not found, using dummy regulator
[ 1.743827] at24 2-0056: supply vcc not found, using dummy regulator
[ 1.793840] at24 2-0057: supply vcc not found, using dummy regulator
[ 1.843578] omap_i2c 4819c000.i2c: bus 2 rev0.11 at 100 kHz
[ 1.863854] gpio gpiochip1: (gpio-32-63): not an immutable chip, please consider fixing it!
[ 1.882287] gpio gpiochip2: (gpio-64-95): not an immutable chip, please consider fixing it!
[ 1.914833] sdhci-omap 481d8000.mmc: supply pbias not found, using dummy regulator
[ 1.928528] platform 4830e000.lcdc: Fixed dependency cycle(s) with /ocp/interconnect@44c00000/segment@200000/target-module@b000/i2c@0/tda19988@70
[ 1.960437] sdhci-omap 481d8000.mmc: supply vqmmc not found, using dummy regulator
[ 1.973055] omap_rng 48310000.rng: Random Number Generator ver. 20
[ 1.979850] random: crng init done
[ 2.060180] davinci_mdio 4a101000.mdio: davinci mdio revision 1.6, bus freq 1000000
[ 2.091480] davinci_mdio 4a101000.mdio: phy[0]: device 4a101000.mdio:00, driver SMSC LAN8710/LAN8720
[ 2.110584] cpsw-switch 4a100000.switch: initialized cpsw ale version 1.4
[ 2.117579] cpsw-switch 4a100000.switch: ALE Table size 1024
[ 2.140272] cpsw-switch 4a100000.switch: cpts: overflow check period 500 (jiffies)
[ 2.148072] cpsw-switch 4a100000.switch: CPTS: ref_clk_freq:250000000 calc_mult:2147483648 calc_shift:29 error:0 nsec/sec
[ 2.180173] cpsw-switch 4a100000.switch: Detected MACID = 94:a9:a8:87:51:b0
[ 2.188519] cpsw-switch 4a100000.switch: initialized (regs 0x4a100000, pool size 256) hw_ver:0019010C 1.12 (0)
[ 2.229769] debugfs: Directory '49000000.dma' with parent 'dmaengine' already present!
[ 2.250155] edma 49000000.dma: TI EDMA DMA engine driver
[ 2.297313] hw perfevents: enabled with armv7_cortex_a8 PMU driver, 5 counters available
[ 2.315287] l3-aon-clkctrl:0000:0: failed to disable
[ 2.323584] gpio gpiochip3: (gpio-96-127): not an immutable chip, please consider fixing it!
[ 2.352148] 44e09000.serial: ttyS0 at MMIO 0x44e09000 (irq = 35, base_baud = 3000000) is a 8250
[ 2.370299] printk: console [ttyS0] enabled
[ 2.370299] printk: console [ttyS0] enabled
[ 2.378811] printk: bootconsole [omap8250] disabled
[ 2.378811] printk: bootconsole [omap8250] disabled
[ 2.451559] tps65217-pmic: Failed to locate of_node [id: -1]
[ 2.463939] tps65217-bl: Failed to locate of_node [id: -1]
[ 2.473026] tps65217 0-0024: TPS65217 ID 0xe version 1.2
[ 2.479822] at24 0-0050: 32768 byte 24c256 EEPROM, writable, 1 bytes/write
[ 2.487493] omap_i2c 44e0b000.i2c: bus 0 rev0.11 at 400 kHz
[ 2.495401] omap_gpio 44e07000.gpio: Could not set line 6 debounce to 200000 microseconds (-22)
[ 2.505969] sdhci-omap 481d8000.mmc: supply pbias not found, using dummy regulator
[ 2.518739] sdhci-omap 481d8000.mmc: supply vqmmc not found, using dummy regulator
[ 2.526538] sdhci-omap 48060000.mmc: Got CD GPIO
[ 2.531437] sdhci-omap 48060000.mmc: supply pbias not found, using dummy regulator
[ 2.550219] sdhci-omap 48060000.mmc: supply vqmmc not found, using dummy regulator
[ 2.596497] mmc0: SDHCI controller on 48060000.mmc [48060000.mmc] using External DMA
[ 2.604398] mmc1: SDHCI controller on 481d8000.mmc [481d8000.mmc] using External DMA
[ 2.614332] Waiting for root device PARTUUID=fff741b0-02...
[ 2.653993] mmc0: new high speed SDHC card at address 59b4
[ 2.661516] mmcblk0: mmc0:59b4 SN32G 29.7 GiB
[ 2.673577] mmcblk0: p1 p2
[ 2.709531] mmc1: new high speed MMC card at address 0001
[ 2.716291] mmcblk1: mmc1:0001 M62704 3.56 GiB
[ 2.723692] mmcblk1: p1 p2
[ 2.727738] mmcblk1boot0: mmc1:0001 M62704 2.00 MiB
[ 2.734892] mmcblk1boot1: mmc1:0001 M62704 2.00 MiB
[ 2.741731] mmcblk1rpmb: mmc1:0001 M62704 512 KiB, chardev (243:0)
[ 2.767055] EXT4-fs (mmcblk0p2): mounted filesystem with ordered data mode. Quota mode: disabled.
[ 2.776563] VFS: Mounted root (ext4 filesystem) on device 179:2.
[ 2.787213] devtmpfs: mounted
[ 2.793406] Freeing unused kernel image (initmem) memory: 1024K
[ 2.800062] Run /sbin/init as init process
INIT: version 3.01 booting
Starting udev
[ 3.936658] udevd[98]: starting version 3.2.10
[ 4.081221] udevd[99]: starting eudev-3.2.10
[ 5.812540] EXT4-fs (mmcblk0p2): re-mounted. Quota mode: disabled.
hwclock: can't open '/dev/misc/rtc': No such file or directory
Fri Mar 9 12:34:56 UTC 2018
hwclock: can't open '/dev/misc/rtc': No such file or directory
Configuring packages on first boot....
(This may take several minutes. Please do not power off the machine.)
Running postinst /etc/rpm-postinsts/100-sysvinit-inittab...
update-rc.d: /etc/init.d/run-postinsts exists during rc.d purge (continuing)
Removing any system startup links for run-postinsts ...
/etc/rcS.d/S99run-postinsts
INIT: Entering runlevel: 5
Configuring network interfaces... [ 7.509344] cpsw-switch 4a100000.switch: starting ndev. mode: dual_mac
[ 7.601269] SMSC LAN8710/LAN8720 4a101000.mdio:00: attached PHY driver (mii_bus:phy_addr=4a101000.mdio:00, irq=POLL)
udhcpc: started, v1.35.0
udhcpc: broadcasting discover
[ 10.751153] cpsw-switch 4a100000.switch eth0: Link is Up - 100Mbps/Full - flow control off
[ 10.759665] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
hwclock: can't open '/dev/misc/rtc': No such file or directory
Starting syslogd/klogd: done

Poky (Yocto Project Reference Distro) 4.0.16 am335x-evm /dev/ttyS0

am335x-evm login:

-----------8<----------------

Then, if I modify the kernel sources and add the following to the bottom of `am335x-boneblack.dts`

&uart5 {
	status = "okay";
};

When the built image is booting I get the following output instead:

--------------8<--------------

U-Boot SPL 2023.04-gd74d0993e2 (Oct 18 2023 - 17:49:46 +0000)
Trying to boot from MMC1

U-Boot 2023.04-gd74d0993e2 (Oct 18 2023 - 17:49:46 +0000)

CPU : AM335X-GP rev 2.1
Model: TI AM335x BeagleBone Black
DRAM: 512 MiB
Core: 160 devices, 18 uclasses, devicetree: separate
WDT: Started wdt@44e35000 with servicing every 1000ms (60s timeout)
NAND: 0 MiB
MMC: OMAP SD/MMC: 0, OMAP SD/MMC: 1
Loading Environment from FAT... Unable to read "uboot.env" from mmc0:1...
<ethaddr> not set. Validating first E-fuse MAC
Net: eth2: ethernet@4a100000, eth3: usb_ether
Hit any key to stop autoboot: 0
switch to partitions #0, OK
mmc0 is current device
Scanning mmc 0:1...
Found /extlinux/extlinux.conf
Retrieving file: /extlinux/extlinux.conf
1: Poky (Yocto Project Reference Distro)
Retrieving file: /extlinux/../zImage
append: root=PARTUUID=e1129d0c-02 rootwait rw earlycon console=ttyO0,115200n8,115200
Retrieving file: /extlinux/../am335x-boneblack.dtb
Kernel image @ 0x82000000 [ 0x000000 - 0x74b200 ]
## Flattened Device Tree blob at 88000000
Booting using the fdt blob at 0x88000000
Working FDT set to 88000000
Loading Device Tree to 8ffe5000, end 8ffffecf ... OK
Working FDT set to 8ffe5000

Starting kernel ...

[ 0.000000] Booting Linux on physical CPU 0x0
[ 0.000000] Linux version 6.1.46-g999 (oe-user@oe-host) (arm-poky-linux-gnueabi-gcc (GCC) 11.4.0, GNU ld (GNU Binutils) 2.38.20220708) #1 PREEMPT Fri Feb 2 19:15:35 UTC 2024
[ 0.000000] CPU: ARMv7 Processor [413fc082] revision 2 (ARMv7), cr=10c5387d
[ 0.000000] CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
[ 0.000000] OF: fdt: Machine model: TI AM335x BeagleBone Black
[ 0.000000] earlycon: omap8250 at MMIO 0x44e09000 (options '')
[ 0.000000] printk: bootconsole [omap8250] enabled
[ 0.000000] Memory policy: Data cache writeback
[ 0.000000] efi: UEFI not found.
[ 0.000000] cma: Reserved 64 MiB at 0x9b800000
[ 0.000000] Zone ranges:
[ 0.000000] Normal [mem 0x0000000080000000-0x000000009fdfffff]
[ 0.000000] HighMem empty
[ 0.000000] Movable zone start for each node
[ 0.000000] Early memory node ranges
[ 0.000000] node 0: [mem 0x0000000080000000-0x000000009fdfffff]
[ 0.000000] Initmem setup node 0 [mem 0x0000000080000000-0x000000009fdfffff]
[ 0.000000] CPU: All CPU(s) started in SVC mode.
[ 0.000000] AM335X ES2.1 (sgx neon)
[ 0.000000] Built 1 zonelists, mobility grouping on. Total pages: 129540
[ 0.000000] Kernel command line: root=PARTUUID=e1129d0c-02 rootwait rw earlycon console=ttyO0,115200n8,115200
[ 0.000000] Dentry cache hash table entries: 65536 (order: 6, 262144 bytes, linear)
[ 0.000000] Inode-cache hash table entries: 32768 (order: 5, 131072 bytes, linear)
[ 0.000000] mem auto-init: stack:off, heap alloc:off, heap free:off
[ 0.000000] Memory: 433560K/522240K available (11264K kernel code, 1470K rwdata, 3264K rodata, 1024K init, 287K bss, 23144K reserved, 65536K cma-reserved, 0K highmem)
[ 0.000000] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
[ 0.000000] trace event string verifier disabled
[ 0.000000] rcu: Preemptible hierarchical RCU implementation.
[ 0.000000] rcu: RCU event tracing is enabled.
[ 0.000000] Trampoline variant of Tasks RCU enabled.
[ 0.000000] rcu: RCU calculated value of scheduler-enlistment delay is 10 jiffies.
[ 0.000000] NR_IRQS: 16, nr_irqs: 16, preallocated irqs: 16
[ 0.000000] IRQ: Found an INTC at 0x(ptrval) (revision 5.0) with 128 interrupts
[ 0.000000] rcu: srcu_init: Setting srcu_struct sizes based on contention.
[ 0.000000] TI gptimer clocksource: always-on /ocp/interconnect@44c00000/segment@200000/target-module@31000
[ 0.000002] sched_clock: 32 bits at 24MHz, resolution 41ns, wraps every 89478484971ns
[ 0.008066] clocksource: dmtimer: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 79635851949 ns
[ 0.018046] TI gptimer clockevent: 24000000 Hz at /ocp/interconnect@48000000/segment@0/target-module@40000
[ 0.029743] Console: colour dummy device 80x30
[ 0.034352] WARNING: Your 'console=ttyO0' has been replaced by 'ttyS0'
[ 0.041137] This ensures that you still see kernel messages. Please
[ 0.047579] update your kernel commandline.
[ 0.051916] Calibrating delay loop... 996.14 BogoMIPS (lpj=4980736)
[ 0.094500] CPU: Testing write buffer coherency: ok
[ 0.099592] CPU0: Spectre v2: using BPIALL workaround
[ 0.104785] pid_max: default: 32768 minimum: 301
[ 0.109714] Mount-cache hash table entries: 1024 (order: 0, 4096 bytes, linear)
[ 0.117241] Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes, linear)
[ 0.126799] cblist_init_generic: Setting adjustable number of callback queues.
[ 0.134311] cblist_init_generic: Setting shift to 0 and lim to 1.
[ 0.140741] Setting up static identity map for 0x80100000 - 0x80100060
[ 0.147606] rcu: Hierarchical SRCU implementation.
[ 0.152558] rcu: Max phase no-delay instances is 1000.
[ 0.159647] EFI services will not be available.
[ 0.164899] devtmpfs: initialized
[ 0.183002] VFP support v0.3: implementor 41 architecture 3 part 30 variant c rev 3
[ 0.191244] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns
[ 0.201398] futex hash table entries: 256 (order: -1, 3072 bytes, linear)
[ 0.213362] pinctrl core: initialized pinctrl subsystem
[ 0.219896] DMI not present or invalid.
[ 0.224504] NET: Registered PF_NETLINK/PF_ROUTE protocol family
[ 0.232900] DMA: preallocated 256 KiB pool for atomic coherent allocations
[ 0.241201] thermal_sys: Registered thermal governor 'step_wise'
[ 0.241307] cpuidle: using governor menu
[ 0.266491] No ATAGs?
[ 0.268931] hw-breakpoint: debug architecture 0x4 unsupported.
[ 0.276971] Serial: AMBA PL011 UART driver
[ 0.310452] SCSI subsystem initialized
[ 0.314975] usbcore: registered new interface driver usbfs
[ 0.328106] usbcore: registered new interface driver hub
[ 0.333615] usbcore: registered new device driver usb
[ 0.348499] pps_core: LinuxPPS API ver. 1 registered
[ 0.353613] pps_core: Software ver. 5.3.6 - Copyright 2005-2007 Rodolfo Giometti <giometti@linux.it>
[ 0.378076] PTP clock support registered
[ 0.382289] EDAC MC: Ver: 3.0.0
[ 0.400158] clocksource: Switched to clocksource dmtimer
[ 0.425632] NET: Registered PF_INET protocol family
[ 0.431055] IP idents hash table entries: 8192 (order: 4, 65536 bytes, linear)
[ 0.450709] tcp_listen_portaddr_hash hash table entries: 1024 (order: 0, 4096 bytes, linear)
[ 0.459428] Table-perturb hash table entries: 65536 (order: 6, 262144 bytes, linear)
[ 0.490169] TCP established hash table entries: 4096 (order: 2, 16384 bytes, linear)
[ 0.498172] TCP bind hash table entries: 4096 (order: 3, 32768 bytes, linear)
[ 0.520203] TCP: Hash tables configured (established 4096 bind 4096)
[ 0.526843] UDP hash table entries: 256 (order: 0, 4096 bytes, linear)
[ 0.540171] UDP-Lite hash table entries: 256 (order: 0, 4096 bytes, linear)
[ 0.547498] NET: Registered PF_UNIX/PF_LOCAL protocol family
[ 0.570646] RPC: Registered named UNIX socket transport module.
[ 0.576747] RPC: Registered udp transport module.
[ 0.590167] RPC: Registered tcp transport module.
[ 0.595002] RPC: Registered tcp NFSv4.1 backchannel transport module.
[ 0.610167] PCI: CLS 0 bytes, default 64
[ 0.621539] Initialise system trusted keyrings
[ 0.640316] workingset: timestamp_bits=30 max_order=17 bucket_order=0
[ 0.662472] squashfs: version 4.0 (2009/01/31) Phillip Lougher
[ 0.680525] NFS: Registering the id_resolver key type
[ 0.685783] Key type id_resolver registered
[ 0.690084] Key type id_legacy registered
[ 0.700339] nfs4filelayout_init: NFSv4 File Layout Driver Registering...
[ 0.707237] nfs4flexfilelayout_init: NFSv4 Flexfile Layout Driver Registering...
[ 0.730198] ntfs: driver 2.1.32 [Flags: R/O].
[ 0.735264] Key type asymmetric registered
[ 0.739489] Asymmetric key parser 'x509' registered
[ 0.760346] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 247)
[ 0.767962] io scheduler mq-deadline registered
[ 0.780172] io scheduler kyber registered
[ 0.878660] Serial: 8250/16550 driver, 5 ports, IRQ sharing enabled
[ 0.902560] STMicroelectronics ASC driver initialized
[ 0.929472] brd: module loaded
[ 0.945793] loop: module loaded
[ 0.964623] CAN device driver interface
[ 0.968953] e1000e: Intel(R) PRO/1000 Network Driver
[ 0.990160] e1000e: Copyright(c) 1999 - 2015 Intel Corporation.
[ 0.996350] igb: Intel(R) Gigabit Ethernet Network Driver
[ 1.010161] igb: Copyright (c) 2007-2014 Intel Corporation.
[ 1.016729] pegasus: Pegasus/Pegasus II USB Ethernet driver
[ 1.030221] usbcore: registered new interface driver pegasus
[ 1.036095] usbcore: registered new interface driver asix
[ 1.060203] usbcore: registered new interface driver ax88179_178a
[ 1.066500] usbcore: registered new interface driver cdc_ether
[ 1.080205] usbcore: registered new interface driver smsc75xx
[ 1.086154] usbcore: registered new interface driver smsc95xx
[ 1.110205] usbcore: registered new interface driver net1080
[ 1.116052] usbcore: registered new interface driver cdc_subset
[ 1.130214] usbcore: registered new interface driver zaurus
[ 1.136016] usbcore: registered new interface driver cdc_ncm
[ 1.150896] usbcore: registered new interface driver usb-storage
[ 1.170664] i2c_dev: i2c /dev entries driver
[ 1.177113] cpuidle: enable-method property 'ti,am3352' found operations
[ 1.200836] sdhci: Secure Digital Host Controller Interface driver
[ 1.207205] sdhci: Copyright(c) Pierre Ossman
[ 1.220396] Synopsys Designware Multimedia Card Interface Driver
[ 1.226731] sdhci-pltfm: SDHCI platform and OF driver helper
[ 1.240679] ledtrig-cpu: registered to indicate activity on CPUs
[ 1.247273] usbcore: registered new interface driver usbhid
[ 1.270155] usbhid: USB HID core driver
[ 1.276708] NET: Registered PF_INET6 protocol family
[ 1.301116] Segment Routing with IPv6
[ 1.304953] In-situ OAM (IOAM) with IPv6
[ 1.309071] sit: IPv6, IPv4 and MPLS over IPv4 tunneling driver
[ 1.320991] NET: Registered PF_PACKET protocol family
[ 1.326199] can: controller area network core
[ 1.350234] NET: Registered PF_CAN protocol family
[ 1.355168] can: raw protocol
[ 1.358218] can: broadcast manager protocol
[ 1.370169] can: netlink gateway - max_hops=1
[ 1.375072] Key type dns_resolver registered
[ 1.379605] ThumbEE CPU extension supported.
[ 1.400174] Registering SWP/SWPB emulation handler
[ 1.405601] omap_voltage_late_init: Voltage driver support not added
[ 1.421085] Loading compiled-in X.509 certificates
[ 1.496701] pinctrl-single 44e10800.pinmux: 142 pins, size 568
[ 1.524998] ti-sysc: probe of 44e31000.target-module failed with error -16
[ 1.562826] ti-sysc: probe of 48040000.target-module failed with error -16
[ 1.602257] gpio gpiochip0: (gpio-0-31): not an immutable chip, please consider fixing it!
[ 1.620528] OMAP GPIO hardware version 0.1
[ 1.651210] at24 2-0054: supply vcc not found, using dummy regulator
[ 1.704244] at24 2-0055: supply vcc not found, using dummy regulator
[ 1.753843] at24 2-0056: supply vcc not found, using dummy regulator
[ 1.803856] at24 2-0057: supply vcc not found, using dummy regulator
[ 1.853572] omap_i2c 4819c000.i2c: bus 2 rev0.11 at 100 kHz
[ 1.874036] 481aa000.serial: ttyS0 at MMIO 0x481aa000 (irq = 25, base_baud = 3000000) is a 8250
[ 1.900187] printk: console [ttyS0] enabled
[ 1.908692] printk: bootconsole [omap8250] disabled

-------------8<---------------

The system still boots, though, and I able to log into it over ssh. Only the serial console seems to be affected.

This worked on linux-ti-staging-5.10 from earlier versions or meta-ti-bsp and we have a board running on linux-5.10 with UART5 enabled without issues.

We are now in the process of updating this board to the latest BSP and would appreciate any hints about how to solve this issue.

Thanks in advance for your help,

António