linux-kernel - Re: [PATCH v8 14/46] x86, mm: use pfn_range_is_mapped() with reserve

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Message-ID: <CAE9FiQWGKdfxceWF9yrtk5K+9bqNmWk=CaWGwffpOq0aZzJWrg@mail.gmail.com>
Date:	Wed, 28 Nov 2012 11:40:19 -0800
From:	Yinghai Lu <yinghai@...nel.org>
To:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...e.hu>,
	"H. Peter Anvin" <hpa@...or.com>, Jacob Shin <jacob.shin@....com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Stefano Stabellini <stefano.stabellini@...citrix.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v8 14/46] x86, mm: use pfn_range_is_mapped() with reserve_initrd

On Wed, Nov 28, 2012 at 9:08 AM, Konrad Rzeszutek Wilk
<konrad.wilk@...cle.com> wrote:
> On Fri, Nov 16, 2012 at 07:38:51PM -0800, Yinghai Lu wrote:
>> We are going to map ram only, so under max_low_pfn_mapped,
>> between 4g and max_pfn_mapped does not mean mapped at all.
>>
>> Use pfn_range_is_mapped() to find out if range is mapped for initrd.
>>
>> That could happen bootloader put initrd in range but user could
>                    ^- 'if the'                              ^^^^^-'used'
>
>> use memmap to carve some of range out.
>   ^^^-> get rid of that.       ^^^^->'ranges'
>
>>
>> Also during copying need to use early_memmap to map original initrd
>> for accessing.

===>
---
We are going to map ram only in patch:
        x86, mm: Only direct map addresses that are marked as E820_RAM

so range under max_low_pfn_mapped, ranges between 4g and max_pfn_mapped
could have holes in them and the holes will not be mapped.

Use pfn_range_is_mapped() to check if range is mapped for initrd.

That could happen if the bootloader put initrd in range but user used
"memmap=" to carve some of ranges out.

Also during copying need to use early_memmap to map original initrd
for accessing.
---
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