linux-kernel - Re: [BUG] Description for memmap in kernel-parameters.txt is wrong

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Message-ID: <52EAA714.3080809@infradead.org>
Date:	Thu, 30 Jan 2014 11:25:08 -0800
From:	Randy Dunlap <rdunlap@...radead.org>
To:	Andiry Xu <andiry@...il.com>, linux-kernel@...r.kernel.org
CC:	Andiry Xu <andiry.xu@...il.com>, Linux MM <linux-mm@...ck.org>
Subject: Re: [BUG] Description for memmap in kernel-parameters.txt is wrong

[adding linux-mm mailing list]

On 01/30/2014 08:52 AM, Andiry Xu wrote:
> Hi,
> 
> In kernel-parameters.txt, there is following description:
> 
> memmap=nn[KMG]$ss[KMG]
>                         [KNL,ACPI] Mark specific memory as reserved.
>                         Region of memory to be used, from ss to ss+nn.

Should be:
                          Region of memory to be reserved, from ss to ss+nn.

but that doesn't help with the problem that you describe, does it?


> Unfortunately this is incorrect. The meaning of nn and ss is reversed.
> For example:
> 
> Command                  Expected                 Result
> memmap 2G$6G        6G - 8G reserved      2G - 8G reserved
> memmap 6G$2G        2G - 8G reserved      6G - 8G reserved

Are you testing on x86?
The code in arch/x86/kernel/e820.c always parses mem_size followed by start address.
I don't (yet) see where it goes wrong...


> Test kernel version 3.13, but I believe the issue has been there long ago.
> 
> I'm not sure whether the description or implementation should be
> fixed, but apparently they do not match.

I prefer to change the documentation and leave the implementation as is.


-- 
~Randy
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