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

From: Randy Dunlap
Date: Thu Jan 30 2014 - 14:25:20 EST


[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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