linux-kernel - Re: [PATCH] mips: kdump: Crash kernel should be able to see old memories

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Message-ID: <bd5b70cf-cfdf-0a4a-dfb5-08e030864138@flygoat.com>
Date:   Tue, 20 Apr 2021 09:11:26 +0800
From:   Jiaxun Yang <jiaxun.yang@...goat.com>
To:     Youling Tang <tangyouling@...ngson.cn>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>
Cc:     linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org,
        Huacai Chen <chenhuacai@...nel.org>
Subject: Re: [PATCH] mips: kdump: Crash kernel should be able to see old
 memories


在 2021/4/19 18:56, Youling Tang 写道:
> From: Huacai Chen <chenhc@...ote.com>
>
> kexec-tools use mem=X@Y to pass usable memories to crash kernel, but in
> commit a94e4f24ec836c8984f83959 ("MIPS: init: Drop boot_mem_map") all
> BIOS passed memories are removed by early_parse_mem(). I think this is
> reasonable for a normal kernel but not for a crash kernel, because a
> crash kernel should be able to see all old memories, even though it is
> not supposed to use them.
>
> Fixes: a94e4f24ec836c8984f83959 ("MIPS: init: Drop boot_mem_map")
> Signed-off-by: Huacai Chen <chenhuacai@...nel.org>
> Signed-off-by: Youling Tang <tangyouling@...ngson.cn>
> ---
>   arch/mips/kernel/setup.c | 2 ++
>   1 file changed, 2 insertions(+)
>
> diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
> index b86e241..ac90d3b 100644
> --- a/arch/mips/kernel/setup.c
> +++ b/arch/mips/kernel/setup.c
> @@ -351,8 +351,10 @@ static int __init early_parse_mem(char *p)
>   	 */
>   	if (usermem == 0) {
>   		usermem = 1;
> +#ifndef CONFIG_CRASH_DUMP

Why depend on a config instead of a runtime variable?

Btw as you are fixing my commit please keep me CCed.


Thanks.


- Jiaxun