linux-kernel - Re: [PATCH 1/2] doc: update mem= option's spec

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Message-ID: <4FDA4816.7000405@landley.net>
Date:	Thu, 14 Jun 2012 15:22:46 -0500
From:	Rob Landley <rob@...dley.net>
To:	Wen Congyang <wency@...fujitsu.com>
CC:	tglx@...utronix.de, Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	bhelgaas@...gle.com, "H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH 1/2] doc: update mem= option's spec

On 06/14/2012 03:10 AM, Wen Congyang wrote:
> Current mem= implementation seems buggy because specification and
> implementation doesn't match. Current mem= has been working
> for many years and it's not buggy, it works as expected. So
> we should update the specification.
> 
> Signed-off-by: Wen Congyang <wency@...fujitsu.com>
> ---
>  Documentation/kernel-parameters.txt |    7 ++++---
>  1 files changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
> index a92c5eb..924b1a4 100644
> --- a/Documentation/kernel-parameters.txt
> +++ b/Documentation/kernel-parameters.txt
> @@ -1471,9 +1471,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
>  	mem=nn[KMG]	[KNL,BOOT] Force usage of a specific amount of memory
>  			Amount of memory to be used when the kernel is not able
>  			to see the whole system memory or for test.
> -			[X86-32] Use together with memmap= to avoid physical
> -			address space collisions. Without memmap= PCI devices
> -			could be placed at addresses belonging to unused RAM.
> +			[X86-32] Work as limiting max address. Use together
> +			with memmap= to avoid physical address space collisions.
> +			Without memmap= PCI devices could be placed at addresses
> +			belonging to unused RAM.
>  
>  	mem=nopentium	[BUGS=X86-32] Disable usage of 4MB pages for kernel
>  			memory.

I have no objection to this but can't confirm it's true or not without
an awful lot more digging through the code I don't have time for right
now. (All the x86-32 machines I've used just had the 640k->1m hole and
the rest was contiguous memory, so the behavior would be the same either
way...)

Sort-of-tentatively-acked-by: Rob Landley <rob@...dley.net>

Rob
-- 
GNU/Linux isn't: Linux=GPLv2, GNU=GPLv3+, they can't share code.
Either it's "mere aggregation", or a license violation.  Pick one.
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