Re: Amiga, serial and SYSRQ

Michael Schmitz
2024-05-19T07:36:50Z

Paolo,

please try adding 'initcall_debug' to the kernel command line.

On a serial console, SysRq is BREAK:

On the serial console (PC style standard serial ports only)
You send a ``BREAK``, then within 5 seconds a command key. Sending
``BREAK`` twice is interpreted as a normal BREAK.

(see Documentation/admin-guide/sysrq.rst)

Cheers,

Michael

Am 19.05.2024 um 06:17 schrieb Paolo Pisati:
> Hi,
>
> what's the key sequence to trigger SYSRQ on Amiga? And what's the sequence if
> i'm redirecting the console via serial?
>
> Some context: i'm trying to collect a backtrace from my Amiga 1200 + Warp
> 1260[1] + flicker fixer that refuses to boot and shows a solid grey screen.
>
> By using a serial, i've seen it booting up to:
>
> ABCDGHIJK
> Linux version 6.6.30-amiga-00006-g809aa9a54cba (flag@amaterasu.local) (m68k-linux-gcc (GCC) 13.1.0, GNU ld (GNU Binutils) 4
> Saving 454 bytes of bootinfo
> printk: console [debug0] enabled
> printk: Too late to register bootconsole debug-1
> Amiga hardware found: [A1200] VIDEO BLITTER AUDIO FLOPPY A1200_IDE KEYBOARD MOUSE SERIAL PARALLEL A2000_CLK CHIP_RAM PAULA
> Zone ranges:
> DMA [mem 0x0000000040000000-0x000004dfffffffff]
> Normal empty
> Movable zone start for each node
> Early memory node ranges
> node 0: [mem 0x0000000040000000-0x000000004dffffff]
> Initmem setup node 0 [mem 0x0000000040000000-0x000000004dffffff]
> pcpu-alloc: s0 r0 d32768 u32768 alloc=1*32768
> pcpu-alloc: [0] 0
> Kernel command line: root=/dev/sda4 debug=ser earlyprintk console=ttyS0,9600n8
> Dentry cache hash table entries: 32768 (order: 5, 131072 bytes, linear)
> Inode-cache hash table entries: 16384 (order: 4, 65536 bytes, linear)
> Sorting __ex_table...
> Built 1 zonelists, mobility grouping on. Total pages: 56840
> mem auto-init: stack:all(zero), heap alloc:off, heap free:off
> Memory: 221284K/229376K available (3753K kernel code, 472K rwdata, 1184K rodata, 172K init, 149K bss, 8092K reserved, 0K c)
> SLUB: HWalign=16, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
> start_kernel::941
> start_kernel::976
> NR_IRQS: 32
> clocksource: ciab: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 2694272661900 ns
> start_kernel::990
> start_kernel::994
> start_kernel::998
> start_kernel::1000
> start_kernel::1006
> start_kernel::1009
>
> I've added some printk around init/main.c::start_kernel() and it *appears* to be
> hanging in "local_irq_enable();".
>
> I've tried all stable LTS kernels from 4.4.y to 6.6.y, and they all shows the same
> exact symptoms.
>
> Hope it rings a bell.
>
> 1: https://amigawarp.eu/product/warp-1260-board-for-amiga-1200/
>