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Subject: Re: [PATCH] docs/kernel-parameters: update description of mem=
To:     Mike Rapoport <rppt@kernel.org>, Jonathan Corbet <corbet@lwn.net>
CC:     Andrew Morton <akpm@linux-foundation.org>,
        "Maciej W. Rozycki" <macro@orcam.me.uk>,
        Mike Rapoport <rppt@linux.ibm.com>,
        Tiezhu Yang <yangtiezhu@loongson.cn>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        <linux-doc@vger.kernel.org>, <linux-mips@vger.kernel.org>,
        <linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>
References: <20220309122446.1118738-1-rppt@kernel.org>
From:   Sergey Shtylyov <s.shtylyov@omp.ru>
Organization: Open Mobile Platform
Message-ID: <d3679148-598e-4b58-96be-e3ab255ab8d9@omp.ru>
Date:   Wed, 9 Mar 2022 19:20:42 +0300
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On 3/9/22 3:24 PM, Mike Rapoport wrote:

> From: Mike Rapoport <rppt@linux.ibm.com>
> 
> The existing description of mem= does not cover all the cases and
> differences between how architectures treat it.
> 
> Extend the description to match the code.
> 
> Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
> ---
> 
> This is in a way a followup for the discussion of mem= usage on MIPS:
> 
> https://lore.kernel.org/all/1646461289-31992-1-git-send-email-yangtiezhu@loongson.cn
> 
>  .../admin-guide/kernel-parameters.txt         | 20 +++++++++++++++++++
>  1 file changed, 20 insertions(+)
> 
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index f5a27f067db9..f3597841a031 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -2834,6 +2834,15 @@
>  			2 when the kernel is not able to see the whole system memory;
>  			3 memory that lies after 'mem=' boundary is excluded from
>  			 the hypervisor, then assigned to KVM guests.
> +			4 to limit the memory available for kdump kernel.
> +
> +			[ARC,MICROBLAZE] - the limit applies only to low memory,
> +			high memory is not affected.
> +
> +			[ARM64] - only limits memory covered by the linear
> +			mapping. The NOMAP regions are not affected.
> +
> +			[HEXAGON] - must be use

   Used?

> to set the memory size, there is

   What? :-)

[...]

MBR, Sergey