linux-kernel - Re: [PATCH] of: unmap memory regions in /memreserve node

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Date:   Tue, 30 Nov 2021 16:43:31 -0600
From:   Rob Herring <robh@...nel.org>
To:     Calvin Zhang <calvinzhang.cool@...il.com>
Cc:     Frank Rowand <frowand.list@...il.com>, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH] of: unmap memory regions in /memreserve node

+linuxppc-dev

On Wed, Nov 24, 2021 at 09:33:47PM +0800, Calvin Zhang wrote:
> Reserved memory regions in /memreserve node aren't and shouldn't
> be referenced elsewhere. So mark them no-map to skip direct mapping
> for them.

I suspect this has a high chance of breaking some platform. There's no 
rule a region can't be accessed.

> 
> Signed-off-by: Calvin Zhang <calvinzhang.cool@...il.com>
> ---
>  drivers/of/fdt.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index bdca35284ceb..9e88cc8445f6 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -638,7 +638,7 @@ void __init early_init_fdt_scan_reserved_mem(void)
>  		fdt_get_mem_rsv(initial_boot_params, n, &base, &size);
>  		if (!size)
>  			break;
> -		early_init_dt_reserve_memory_arch(base, size, false);
> +		early_init_dt_reserve_memory_arch(base, size, true);
>  	}
>  
>  	fdt_scan_reserved_mem();
> -- 
> 2.30.2
> 
>