Re: Kernel versions 6.x don't boot on Amiga 4000

Geert Uytterhoeven
2023-02-27T09:10:17Z

Hi Finn,

FTR, here is the diff of the dmesg between good and bad:

+initrd: 07f61166 - 08000000

This is wrong (note the 6 trailing zeros), as phys_to_virt() is not
working correctly yet (module_fixup() is called from paging_init()).

Zone ranges:
DMA [mem 0x0000000007400000-0x0000007fffffffff]
Normal empty
Movable zone start for each node
Early memory node ranges
node 0: [mem 0x0000000007400000-0x0000000007ffffff]
Initmem setup node 0 [mem 0x0000000007400000-0x0000000007ffffff]
-initrd: 00b61166 - 00c00000

This is correct (note the 5 trailing zeros).

-pcpu-alloc: s0 r0 d32768 u32768 alloc=1*32768
-pcpu-alloc: [0] 0
[...]
+Unable to handle kernel access at virtual address (ptrval)
+Oops: 00000000
+Modules linked in:
+PC: [<002c11be>] memcmp+0x2c/0x5c
+SR: 2700 SP: (ptrval) a2: 003bd560
+d0: 0035eb83 d1: 07fffff8 d2: 002c1192 d3: 000000e6
+d4: 000684e8 d5: 00447000 a0: 0000000c a1: 07fffff4
+Process swapper (pid: 0, task=(ptrval))
+Frame format=7 eff addr=003bbfbc ssw=0505 faddr=07fffff4
+wb 1 stat/addr/data: 0005 00447000 07401000
+wb 2 stat/addr/data: 0005 000000e6 000684e8
+wb 3 stat/addr/data: 0005 003bbfb4 002c1192
+push data: 07401000 002c7d82 07401000 074a2cf4
+Stack from 003bbfb4:
+002c1192 000000e6 002c7d82 00428eda 07fffff4 0035eb7f 0000000c 00447000
+000000e6 000684e8 00447000 07401000 074bec08 07401000 074a2cf4 07fffff0
+00440406 00000000 00428322
+Call Trace: [<002c1192>] memcmp+0x0/0x5c
+[<002c7d82>] _printk+0x0/0x18
+[<00428eda>] start_kernel+0x80/0x5b0
+[<000684e8>] pcpu_alloc+0x88/0x3b4
+[<00428322>] _sinittext+0x322/0x9b0

On Mon, Feb 27, 2023 at 7:30 AM Finn Thain <fthain@linux-m68k.org> wrote:
> On Mon, 27 Feb 2023, Michael Schmitz wrote:
> > I wonder whether Finn's memtest patch merely exposed another MM bug
>
> A kernel patch may be easier than a bootloader patch (even if this is a
> bootloader bug) particularly if it affects multiple platforms.
>
> A partial revert of my patch (below) will probably avoid the issue, but
> with the side effect that use of memtest will clobber the initrd.

Which we can avoid, by moving the ramdisk handling inside paging_init().

> The initrd and memtest features aren't usually needed together. At the
> time when I needed the memtest feature I did not have confidence in the
> hardeare. An initrd wasn't very useful at that point.
>
> diff --git a/arch/m68k/kernel/setup_mm.c b/arch/m68k/kernel/setup_mm.c
> index 3a2bb2e8fdad..92f1b9268dff 100644
> --- a/arch/m68k/kernel/setup_mm.c
> +++ b/arch/m68k/kernel/setup_mm.c
> @@ -326,6 +326,8 @@ void __init setup_arch(char **cmdline_p)
> panic("No configuration setup");
> }
>
> + paging_init();
> +
> #ifdef CONFIG_BLK_DEV_INITRD
> if (m68k_ramdisk.size) {
> memblock_reserve(m68k_ramdisk.addr, m68k_ramdisk.size);

Presumably something in memblock_reserve() relies on having
called paging_init() before?

I'll do some more debugging later today...

> @@ -335,8 +337,6 @@ void __init setup_arch(char **cmdline_p)
> }
> #endif
>
> - paging_init();
> -
> #ifdef CONFIG_NATFEAT
> nf_init();
> #endif
>

--
Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds