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List:       linux-arm-kernel
Subject:    Re: [PATCH] WIP: HACK: LPAE, BOOTMEM and NO_BOOTMEM
From:       Yinghai Lu <yinghai () kernel ! org>
Date:       2013-06-29 20:08:13
Message-ID: CAE9FiQUoVNvWmmTV2+ZkU_nMxFToTHw6QLwp_Z_EjwMzqdLwuA () mail ! gmail ! com
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On Sat, Jun 29, 2013 at 12:55 PM, Russell King - ARM Linux
<linux@arm.linux.org.uk> wrote:
> On Sat, Jun 29, 2013 at 12:29:55PM -0700, Yinghai Lu wrote:
>> >> On these SoCs which Santosh is working on, the main physical memory
>> >> mapping is above 4GB, with just a small alias below 4GB to allow the
>> >> system to boot without the MMU being on, as they may have more than
>> >> 4GB of RAM.  As I understand it, the small alias below 4GB is not
>> >> suitable for use as a "lowmem" mapping.
>>
>> is that 32bit ARM or 64bit ARM?
>
> Only 32-bit has LPAE.  Such things don't make sense on 64-bit CPUs.

32bit ARM does not support NO_BOOTMEM yet.

arch/arc/Kconfig:       select NO_BOOTMEM
arch/arm64/Kconfig:     select NO_BOOTMEM
arch/sparc/Kconfig:     select NO_BOOTMEM
arch/x86/Kconfig:config NO_BOOTMEM


so may need to
1. make 32bit ARM to use NO_BOOTMEM at first.

2 .we can add alloc_memblock as MACRO or inline for bootmem arches,

3. NO_BOOTMEM arches will have alloc_memblock in nobootmem.c

4. replace alloc_bootmem calling with alloc_memblock calling in core code.

Thanks

Yinghai

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