linux-kernel - Re: [PATCH 3/5] x86: Only direct map addresses that are marked as E820

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Date:	Fri, 24 Aug 2012 23:20:20 -0500
From:	Jacob Shin <jacob.shin@....com>
To:	"H. Peter Anvin" <hpa@...or.com>
CC:	X86-ML <x86@...nel.org>, LKML <linux-kernel@...r.kernel.org>,
	Yinghai Lu <yinghai@...nel.org>, Tejun Heo <tj@...nel.org>,
	Dave Young <dyoung@...hat.com>,
	Chao Wang <chaowang@...hat.com>,
	Vivek Goyal <vgoyal@...hat.com>,
	Andreas Herrmann <andreas.herrmann3@....com>,
	Borislav Petkov <borislav.petkov@....com>
Subject: Re: [PATCH 3/5] x86: Only direct map addresses that are marked as
 E820_RAM

On Fri, Aug 24, 2012 at 06:13:02PM -0700, H. Peter Anvin wrote:
> On 08/24/2012 05:49 PM, Jacob Shin wrote:
> > 
> > Right, I think what I was attempting to do was to merge the 1MB
> > with E820_RAM right above 1MB:
> > 
> > So instead of:
> > 
> > init_memory_mapping(0, 1MB)
> > init_memory_mapping(1MB, 2GB)
> > 
> > It would be:
> > 
> > init_memory_mapping(0, 2GB)
> > 
> > While taking care of the odd case where there is a gap right after
> > 1MB.
> > 
> > But if its not worth it, I can move it out of the loop.
> > 
> 
> What is the benefit?

So that in the case where we have E820_RAM right above 1MB, we don't
call init_memory_mapping twice, first on 0 ~ 1MB and then 1MB ~ something

we only call it once. 0 ~ something.

I'll get it out of the loop if you don't think its a good idea.

> 
> 	-hpa
> 
> 

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