[PATCH 1/3] MIPS: Crash kernel should be able to see old memories

[Baoquan He]

On 09/23/20 at 10:30am, Huacai Chen wrote:
> Kexec-tools use mem=X at 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.

I am not familiar with MIPS code, but we analyze and fill memmap= to
pass usable memory to crashkenrel in kexec-tools, do you mean you are
specifying memmap= or mem= by hand?

And we don't have mem=X at Y, only mem=nn[KMG].

> 
> Fixes: a94e4f24ec836c8984f83959 ("MIPS: init: Drop boot_mem_map")
> Signed-off-by: Huacai Chen <chenhc at lemote.com>
> ---
>  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 4c04a86..e2804a2 100644
> --- a/arch/mips/kernel/setup.c
> +++ b/arch/mips/kernel/setup.c
> @@ -392,8 +392,10 @@ static int __init early_parse_mem(char *p)
>  	 */
>  	if (usermem == 0) {
>  		usermem = 1;
> +#ifndef CONFIG_CRASH_DUMP
>  		memblock_remove(memblock_start_of_DRAM(),
>  			memblock_end_of_DRAM() - memblock_start_of_DRAM());
> +#endif
>  	}
>  	start = 0;
>  	size = memparse(p, &p);
> -- 
> 2.7.0
>