linux-kernel - Re: [PATCH 01/11] x86/kernel: remove conditional early remap in parse_e820

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Message-ID: <4D09E207.8080001@linutronix.de>
Date:	Thu, 16 Dec 2010 10:55:19 +0100
From:	Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:	"H. Peter Anvin" <hpa@...or.com>
CC:	linux-kernel@...r.kernel.org, sodaville@...utronix.de,
	x86@...nel.org, Dirk Brandewie <dirk.brandewie@...il.com>
Subject: Re: [PATCH 01/11] x86/kernel: remove conditional early remap in parse_e820_ext

H. Peter Anvin wrote:
> 
> I like the fact that this puts all the mapping in the same layer, but I
> also think it's unfortunate to discard the optimization of always
> mapping the minimum of <header length, rest of page>; your code will
> *always* map-unmap-map the code, even in the (presumably very common)
> case of the data fitting on a single page.

Okay, I will take this into account.

> Furthermore, your code retains a minor bug from the original code, which
> is that if the header is not page-aligned, it may be needlessly map more
> than one page with unknown content.

I just checked that early_memremap() maps the memory if it is not on a
page boundary. I take care of this.

> I also found your patch description to be needlessly hard to follow.
> The key point is that it puts all the map manipulation into
> parse_setup_data() where it belongs.  Since you're changing an
> interface, however, also do note that you have checked that there are no
> other callers to parse_e820_ext().

okay.

> 	-hpa


Sebastian
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