linux-kernel - Re: [PATCH][Regression] x86, 32-bit: trim memory not covered by wb mtrrs

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Message-Id: <200802071705.59601.balajirrao@gmail.com>
Date:	Thu, 7 Feb 2008 17:05:59 +0530
From:	Balaji Rao <balajirrao@...il.com>
To:	"Yinghai Lu" <yhlu.kernel@...il.com>
Cc:	"Ingo Molnar" <mingo@...e.hu>, linux-kernel@...r.kernel.org,
	"Thomas Gleixner" <tglx@...utronix.de>, jesse.barnes@...el.com,
	ak@...e.de
Subject: Re: [PATCH][Regression] x86, 32-bit: trim memory not covered by wb mtrrs - FIX

On Thursday 07 February 2008 02:20:35 pm Yinghai Lu wrote:
<snip>
> > Cool! Yes, Yinghai Lu's patch indeed is the same as mine and its really
> > surprising that we've used the same variable name too! :)
>
> minor difference
> +               trim_start = highest_pfn << PAGE_SHIFT;
> +               trim_size = end_pfn << PAGE_SHIFT;
>
> could cause some problem with 32 bit kernel when mem > 4g.
> becase highest_pfn and end_pfn is unsigned long aka 32 bit ...could
> overflow.
>
> so need to assign thtem to trim_start/trim_end at first
> or
> +               trim_start = (u64)highest_pfn << PAGE_SHIFT;
> +               trim_size = (u64)end_pfn << PAGE_SHIFT;
>

Yea right.. Thanks for pointing that out.

-- 
regards,
balaji rao
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