Hi,
On Wed, Apr 28, 2021 at 11:33:24AM +1000, Jordan Niethe wrote:
> On Mon, Apr 26, 2021 at 1:40 AM Jonathan Neuschäfer
> <j.neuschae...@gmx.net> wrote:
> >
> > Hi,
> >
> > I recently booted my Wii again, and I noticed a regression at boot time.
> > Output stops after the "Finalizing device tree... flat tree at 0xXXXXXX"
> > message. I bisected it to this commit in the 5.8 development cycle:
> >
> > commit 7c95d8893fb55869882c9f68f4c94840dc43f18f
> > Author: Jordan Niethe <jniet...@gmail.com>
> > Date: Wed May 6 13:40:25 2020 +1000
> >
> > powerpc: Change calling convention for create_branch() et. al.
[...]
> > Do you have any hints on how to debug and/or fix this issue?
> Thanks for bisecting and reporting.
> The "Finalizing device tree... flat tree at 0xXXXXXX" message comes
> from the bootwrapper so if that is the last output it must be crashing
> pretty early.
> Commit 7c95d8893fb5 ("powerpc: Change calling convention for
> create_branch() et. al.") made a change to machine_init() in
> setup_32.c which seems like it might be a likely culprit for causing
> early crashing.
> The branch that is created and patched is just for optimization, so to
> see if that is in fact the problem it might be worth trying to boot
> with a patch like below
>
> diff --git a/arch/powerpc/kernel/setup_32.c b/arch/powerpc/kernel/setup_32.c
> --- a/arch/powerpc/kernel/setup_32.c
> +++ b/arch/powerpc/kernel/setup_32.c
> @@ -87,9 +87,6 @@ notrace void __init machine_init(u64 dt_ptr)
>
> patch_instruction_site(&patch__memcpy_nocache,
> ppc_inst(PPC_INST_NOP));
>
> - create_cond_branch(&insn, addr, branch_target(addr), 0x820000);
> - patch_instruction(addr, insn); /* replace b by bne cr0 */
> -
> /* Do some early initialization based on the flat device tree */
> early_init_devtree(__va(dt_ptr));This brings no improvement, unfortunately. The output is still: top of MEM2 @ 13F00000 zImage starting: loaded at 0x00b00000 (sp: 0x01145f90) Allocating 0xae3970 bytes for kernel... Decompressing (0x00000000 <- 0x00b11000:0x01143576)... Done! Decompressed 0xa65fdc bytes Linux/PowerPC load: root=/dev/mmcblk0p2 rootwait console=usbgecko1 Finalizing device tree... flat tree at 0x11467a0 I'll probably dig deeper next weekend. Jonathan
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