linux-kernel - Re: [PATCH] m68k: Enable memtest functionality

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Date:   Fri, 12 Nov 2021 09:05:31 +0100
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Finn Thain <fthain@...ux-m68k.org>
Cc:     Mike Rapoport <rppt@...nel.org>, Sam Creasey <sammy@...my.net>,
        Jonathan Corbet <corbet@....net>,
        "open list:DOCUMENTATION" <linux-doc@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-m68k <linux-m68k@...ts.linux-m68k.org>
Subject: Re: [PATCH] m68k: Enable memtest functionality

Hi Finn,

On Fri, Nov 12, 2021 at 1:37 AM Finn Thain <fthain@...ux-m68k.org> wrote:
> Enable the memtest functionality and rearrange some code to prevent it
> from clobbering the initrd.
>
> The CONFIG_BLK_DEV_INITRD symbol was conditional on !defined(CONFIG_SUN3).
> For simplicity, remove that test on the basis that m68k_ramdisk.size == 0
> on Sun 3.
>
> The SLIME source code at
> http://sammy.net/sun3/ftp/pub/m68k/sun3/slime/slime-2.0.tar.gz
> indicates that no BI_RAMDISK entry is ever passed to the kernel due
> to #ifdef 0 around the relevant code.
>
> Cc: Mike Rapoport <rppt@...nel.org>
> Cc: Sam Creasey <sammy@...my.net>
> Cc: Jonathan Corbet <corbet@....net>
> Signed-off-by: Finn Thain <fthain@...ux-m68k.org>

Thanks for your patch!

> --- 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

if MMU_MOTOROLA?

>         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/kernel/setup_mm.c b/arch/m68k/kernel/setup_mm.c
> index 4b51bfd38e5f..49e573b94326 100644
> --- a/arch/m68k/kernel/setup_mm.c
> +++ b/arch/m68k/kernel/setup_mm.c
> @@ -338,13 +338,6 @@ void __init setup_arch(char **cmdline_p)
>                 panic("No configuration setup");
>         }
>
> -       paging_init();
> -
> -#ifdef CONFIG_NATFEAT
> -       nf_init();
> -#endif
> -
> -#ifndef CONFIG_SUN3
>  #ifdef CONFIG_BLK_DEV_INITRD
>         if (m68k_ramdisk.size) {
>                 memblock_reserve(m68k_ramdisk.addr, m68k_ramdisk.size);

Does this still work, given the initrd is part of memory that used
to be added before (in paging_init(), but now is added later?
(I'm no memblock expert, so that might be a silly question ;-)

> @@ -354,6 +347,12 @@ void __init setup_arch(char **cmdline_p)
>         }
>  #endif
>
> +       paging_init();
> +
> +#ifdef CONFIG_NATFEAT
> +       nf_init();
> +#endif
> +
>  #ifdef CONFIG_ATARI
>         if (MACH_IS_ATARI)
>                 atari_stram_reserve_pages((void *)availmem);
> @@ -364,8 +363,6 @@ void __init setup_arch(char **cmdline_p)
>         }
>  #endif
>
> -#endif /* !CONFIG_SUN3 */
> -
>  /* set ISA defs early as possible */
>  #if defined(CONFIG_ISA) && defined(MULTI_ISA)
>         if (MACH_IS_Q40) {
> diff --git a/arch/m68k/mm/motorola.c b/arch/m68k/mm/motorola.c
> index 9f3f77785aa7..5b6575eb6d02 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);

So this is available only if MMU_MOTOROLA, not for Sun-3, Coldfire,
or nommu.

> +
>         /*
>          * initialize the bad page table and bad page to point
>          * to a couple of allocated pages

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-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