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From:   Michael Ellerman <mpe@ellerman.id.au>
To:     Christophe Leroy <christophe.leroy@c-s.fr>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>
Cc:     linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH] powerpc/prom: move the device tree if not in declared memory.
In-Reply-To: <9e06c82e76e8e29cb1ae0b989f3bbbb6b2099e03.1545053638.git.christophe.leroy@c-s.fr>
References: <9e06c82e76e8e29cb1ae0b989f3bbbb6b2099e03.1545053638.git.christophe.leroy@c-s.fr>
Date:   Wed, 19 Dec 2018 15:42:50 +1100
Message-ID: <871s6erut1.fsf@concordia.ellerman.id.au>
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Sender: linux-kernel-owner@vger.kernel.org
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Christophe Leroy <christophe.leroy@c-s.fr> writes:

> If the device tree doesn't reside in the memory which is declared
> inside it, it has to be moved as well as this memory will not be
> mapped by the kernel.

I worry this will break some obscure platform, but I'll merge it anyway
and we'll see :)

cheers

> diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
> index 87a68e2dc531..4181ec715f88 100644
> --- a/arch/powerpc/kernel/prom.c
> +++ b/arch/powerpc/kernel/prom.c
> @@ -124,8 +124,8 @@ static void __init move_device_tree(void)
>  	size = fdt_totalsize(initial_boot_params);
>  
>  	if ((memory_limit && (start + size) > PHYSICAL_START + memory_limit) ||
> -			overlaps_crashkernel(start, size) ||
> -			overlaps_initrd(start, size)) {
> +	    !memblock_is_memory(start + size - 1) ||
> +	    overlaps_crashkernel(start, size) || overlaps_initrd(start, size)) {
>  		p = __va(memblock_phys_alloc(size, PAGE_SIZE));
>  		memcpy(p, initial_boot_params, size);
>  		initial_boot_params = p;
> -- 
> 2.13.3