SpacemiT k1: Linux crashes setting up smp with mainline U-Boot

[Michael Opdenacker <michael.opdenacker@rootcommit.com>]

Greetings,

I'm trying to boot mainline Linux with *mainline* U-Boot on SpacemiT K1 
(Banana Pi F3) and I'm very close!

Since mainline U-Boot supports Banana Pi F3 without mmc for the moment, 
I tweaked u-boot.itb to include the Linux kernel and k1-bananapi-f3.dtb 
binaries, so that they are loaded into RAM by U-Boot SPL 2022.10spacemit 
(sorry, this part with DRAM training is still vendor specific).

Here's what I get so far:

U-Boot 2026.01-rc4 (Dec 10 2025 - 15:28:43 +0000)

DRAM:  4 GiB
Core:  21 devices, 9 uclasses, devicetree: separate
MMC:
Loading Environment from EXT4... In:    serial@d4017000
Out:   serial@d4017000
Err:   serial@d4017000
Net:   No ethernet found.
=> setenv bootargs console=ttyS0,115200 earlycon=sbi
=> booti 0x2000000 - 0x5000000
Moving Image from 0x2000000 to 0x200000, end=0x1a7d000
## Flattened Device Tree blob at 05000000
    Booting using the fdt blob at 0x5000000
Working FDT set to 5000000
    Loading Device Tree to 000000007df41000, end 000000007df49dff ... OK
Working FDT set to 7df41000

Starting kernel ...

[    0.000000] Booting Linux on hartid 0
[    0.000000] Linux version 6.18.0-12930-gd358e5254674 (mike@a8) 
(Ubuntu clang version 18.1.3 (1ubuntu1), Ubuntu LLD 18.1.3) #24 SMP Thu 
Dec 11 20:26:18 CET 2025
[    0.000000] Machine model: Banana Pi BPI-F3
[    0.000000] SBI specification v3.0 detected
[    0.000000] SBI implementation ID=0x1 Version=0x10007
[    0.000000] SBI TIME extension detected
[    0.000000] SBI IPI extension detected
[    0.000000] SBI RFENCE extension detected
[    0.000000] SBI DBCN extension detected
[    0.000000] SBI FWFT extension detected
[    0.000000] earlycon: sbi0 at I/O port 0x0 (options '')
[    0.000000] printk: legacy bootconsole [sbi0] enabled
[    0.000000] efi: UEFI not found.
[    0.000000] OF: reserved mem: 0x0000000000000000..0x000000000003ffff 
(256 KiB) nomap non-reusable mmode_resv0@0
[    0.000000] OF: reserved mem: 0x0000000000040000..0x000000000007ffff 
(256 KiB) nomap non-reusable mmode_resv1@40000
[    0.000000] Zone ranges:
[    0.000000]   DMA32    [mem 0x0000000000000000-0x00000000ffffffff]
[    0.000000]   Normal   [mem 0x0000000100000000-0x000000017fffffff]
[    0.000000] Movable zone start for each node
[    0.000000] Early memory node ranges
[    0.000000]   node   0: [mem 0x0000000000000000-0x000000000007ffff]
[    0.000000]   node   0: [mem 0x0000000000080000-0x000000007fffffff]
[    0.000000]   node   0: [mem 0x0000000100000000-0x000000017fffffff]
[    0.000000] Initmem setup node 0 [mem 
0x0000000000000000-0x000000017fffffff]
[    0.000000] SBI HSM extension detected
[    0.000000] riscv: base ISA extensions acdfimv
[    0.000000] riscv: ELF capabilities acdfimv
[    0.000000] Ticket spinlock: enabled
[    0.000000] percpu: Embedded 31 pages/cpu s86808 r8192 d31976 u126976
[    0.000000] Kernel command line: console=ttyS0,115200 earlycon=sbi
[    0.000000] printk: log buffer data + meta data: 131072 + 458752 = 
589824 bytes
[    0.000000] Dentry cache hash table entries: 524288 (order: 10, 
4194304 bytes, linear)
[    0.000000] Inode-cache hash table entries: 262144 (order: 9, 2097152 
bytes, linear)
[    0.000000] software IO TLB: area num 8.
[    0.000000] software IO TLB: mapped [mem 
0x0000000079f41000-0x000000007df41000] (64MB)
[    0.000000] Built 1 zonelists, mobility grouping on.  Total pages: 
1048576
[    0.000000] mem auto-init: stack:all(zero), heap alloc:off, heap free:off
[    0.000000] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=8, Nodes=1
[    0.000000] rcu: Hierarchical RCU implementation.
[    0.000000] rcu:     RCU event tracing is enabled.
[    0.000000] rcu:     RCU restricting CPUs from NR_CPUS=64 to 
nr_cpu_ids=8.
[    0.000000]     Tracing variant of Tasks RCU enabled.
[    0.000000] rcu: RCU calculated value of scheduler-enlistment delay 
is 25 jiffies.
[    0.000000] rcu: Adjusting geometry for rcu_fanout_leaf=16, nr_cpu_ids=8
[    0.000000] RCU Tasks Trace: Setting shift to 3 and lim to 1 
rcu_task_cb_adjust=1 rcu_task_cpu_ids=8.
[    0.000000] NR_IRQS: 64, nr_irqs: 64, preallocated irqs: 0
[    0.000000] riscv-intc: 64 local interrupts mapped
[    0.000000] riscv: providing IPIs using SBI IPI extension
[    0.000000] rcu: srcu_init: Setting srcu_struct sizes based on 
contention.
[    0.000000] clocksource: riscv_clocksource: mask: 0xffffffffffffffff 
max_cycles: 0x588fe9dc0, max_idle_ns: 440795202592 ns
[    0.000001] sched_clock: 64 bits at 24MHz, resolution 41ns, wraps 
every 4398046511097ns
[    0.008110] riscv-timer: Timer interrupt in S-mode is available via 
sstc extension
[    0.016005] Console: colour dummy device 80x25
[    0.020354] Calibrating delay loop (skipped), value calculated using 
timer frequency.. 48.00 BogoMIPS (lpj=96000)
[    0.030683] pid_max: default: 32768 minimum: 301
[    0.035614] Mount-cache hash table entries: 8192 (order: 4, 65536 
bytes, linear)
[    0.042860] Mountpoint-cache hash table entries: 8192 (order: 4, 
65536 bytes, linear)
[    0.052920] riscv: ELF compat mode unsupported
[    0.052947] ASID allocator using 16 bits (65536 entries)
[    0.060752] rcu: Hierarchical SRCU implementation.
[    0.065510] rcu:     Max phase no-delay instances is 1000.
[    0.070983] Timer migration: 1 hierarchy levels; 8 children per 
group; 1 crossnode level
[    0.079110] EFI services will not be available.
syys 0.083956] smp: Bringing upsysysys: sys: 0xss
1.  sys:t:: r  y00 xxs01fxdcfe121.0
210c.

   b0
m:3
j...


Here, the machine gets back to U-Boot SPL.

If I add "maxcpus=1", the kernel boots to completion (yoohoo!). This 
shows there's an issue with SMP setup.

With the same kernel and DTB, this doesn't happen with the SpacemiT 
version of U-Boot.

Any clue what could happen here? As anyone experience anything similar?

Note that I'm using the latest mainline kernel (pre 6.19-rc1) and 
mainlne U-Boot.

Note that this works exactly the same on Orange Pi RV2 (yoohoo!), so 
once this works, I'll sent a patch to mainline U-Boot to support Orange 
Pi RV2 too :D

Thanks in advance for your tips
Cheers
Michael.

-- 
Michael Opdenacker
Root Commit
Yocto Project and OpenEmbedded Training course - Learn by doing:
https://rootcommit.com/training/yocto/


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