From: sshtylyov@ru.mvista.com (Sergei Shtylyov)
Date: Tue, 06 Mar 2012 21:06:40 +0300
Subject: [PATCH 6/6] ARM: mm: truncate memory banks to fit in 4GB space
 for classic MMU
In-Reply-To: <1331052846-19144-7-git-send-email-will.deacon@arm.com>
References: <1331052846-19144-1-git-send-email-will.deacon@arm.com>
 <1331052846-19144-7-git-send-email-will.deacon@arm.com>
Message-ID: <4F565230.6030800@ru.mvista.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

Hello.

On 03/06/2012 07:54 PM, Will Deacon wrote:

> If a bank of memory spanning the 4GB boundary is added on a !CONFIG_LPAE
> kernel then we will hang early during boot since the memory bank will
> have wrapped around to zero.

> This patch truncates memory banks for !LPAE configurations when the end
> address is not representable in 32 bits.

> Signed-off-by: Will Deacon<will.deacon@arm.com>
> ---
>   arch/arm/kernel/setup.c |   11 ++++++++++-
>   1 files changed, 10 insertions(+), 1 deletions(-)

> diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
> index a255c39..aeaa048 100644
> --- a/arch/arm/kernel/setup.c
> +++ b/arch/arm/kernel/setup.c
> @@ -521,7 +521,16 @@ int __init arm_add_memory(phys_addr_t start, unsigned long size)
>   	 */
>   	size -= start&  ~PAGE_MASK;
>   	bank->start = PAGE_ALIGN(start);
> -	bank->size  = size&  PAGE_MASK;
> +
> +#ifndef CONFIG_LPAE
> +	if (bank->start + size<  bank->start) {
> +		printk(KERN_CRIT "Truncating memory at 0x%08llx to fit in "
> +			"32-bit physical address space\n", (long long)start);
> +		size = ULONG_MAX - bank->start;

    I think you forgot to add one here.

WBR, Sergei