Re: [RFC] m68k: Enable memtest kernel parameter

[Michael Schmitz <schmitzmic@gmail.com>]

Hi Finn,

On 13/09/21 13:34, Finn Thain wrote:
>
> This appears to work on Aranym, QEMU and the Quadra 630 I have here.
> It is completely untested on Coldfire etc. I don't even know whether the
> right memory mappings are in place for this to actually work as intended.

The comment just above the section from paging_init() in your patch 
states that all physical memory is mapped into kernel virtual address 
space. I don't think that mapping is contiguous though.

> Would someone take a look please?
>
> diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig
> index 6e40f7f29ebc..d87e12b4855b 100644
> --- a/arch/m68k/Kconfig
> +++ b/arch/m68k/Kconfig
> @@ -9,6 +9,7 @@ config M68K
>  	select ARCH_HAVE_NMI_SAFE_CMPXCHG if RMW_INSNS
>  	select ARCH_MIGHT_HAVE_PC_PARPORT if ISA
>  	select ARCH_NO_PREEMPT if !COLDFIRE
> +	select ARCH_USE_MEMTEST
>  	select ARCH_WANT_IPC_PARSE_VERSION
>  	select BINFMT_FLAT_ARGVP_ENVP_ON_STACK
>  	select DMA_DIRECT_REMAP if HAS_DMA && MMU && !COLDFIRE
> diff --git a/arch/m68k/mm/motorola.c b/arch/m68k/mm/motorola.c
> index 3a653f0a4188..d6301a094fc1 100644
> --- a/arch/m68k/mm/motorola.c
> +++ b/arch/m68k/mm/motorola.c
> @@ -455,6 +455,8 @@ void __init paging_init(void)
>
>  	flush_tlb_all();
>
> +	early_memtest(min_addr, max_addr);
> +
>  	/*
>  	 * initialize the bad page table and bad page to point
>  	 * to a couple of allocated pages
>

I'd rather start that from availmem, not from min_addr ... I'm amazed 
this works - I'd expect the kernel text segment to get trashed by the 
memory test routines.

Cheers,

	Michael