linux-kernel - Re: [PATCH 02/35] mm: support direct memory reservation

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Date:   Thu, 8 Oct 2020 13:34:10 -0700
From:   Randy Dunlap <rdunlap@...radead.org>
To:     yulei.kernel@...il.com, akpm@...ux-foundation.org,
        naoya.horiguchi@....com, viro@...iv.linux.org.uk,
        pbonzini@...hat.com
Cc:     linux-fsdevel@...r.kernel.org, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, xiaoguangrong.eric@...il.com,
        kernellwp@...il.com, lihaiwei.kernel@...il.com,
        Yulei Zhang <yuleixzhang@...cent.com>,
        Xiao Guangrong <gloryxiao@...cent.com>
Subject: Re: [PATCH 02/35] mm: support direct memory reservation

On 10/8/20 12:53 AM, yulei.kernel@...il.com wrote:
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index a1068742a6df..da15d4fc49db 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -980,6 +980,44 @@
>  			The filter can be disabled or changed to another
>  			driver later using sysfs.
>  
> +	dmem=[!]size[KMG]
> +			[KNL, NUMA] When CONFIG_DMEM is set, this means
> +			the size of memory reserved for dmemfs on each numa

			                                               NUMA

> +			memory node and 'size' must be aligned to the default
> +			alignment that is the size of memory section which is
> +			128M on default on x86_64. If set '!', such amount of

			     by default

> +			memory on each node will be owned by kernel and dmemfs
> +			own the rest of memory on each node.

			owns

> +			Example: Reserve 4G memory on each node for dmemfs
> +				dmem = 4G

IIRC, you don't want spaces in this example.
Or did you check? Does the kernel's command line parser accept & ignore spaces like these?


> +
> +	dmem=[!]size[KMG]:align[KMG]
> +			[KNL, NUMA] Ditto. 'align' should be power of two and
> +			it's not smaller than the default alignment. Also

	drop "it's"

> +			'size' must be aligned to 'align'.
> +			Example: Bad dmem parameter because 'size' misaligned
> +				dmem=0x40200000:1G
> +
> +	dmem=size[KMG]@addr[KMG]
> +			[KNL] When CONFIG_DMEM is set, this marks specific
> +			memory as reserved for dmemfs. Region of memory will be
> +			used by dmemfs, from addr to addr + size. Reserving a
> +			certain memory region for kernel is illegal so '!' is
> +			forbidden. Should not assign 'addr' to 0 because kernel
> +			will occupy fixed memory region begin at 0 address.

			                                beginning

> +			Ditto, 'size' and 'addr' must be aligned to default
> +			alignment.
> +			Example: Exclude memory from 5G-6G for dmemfs.
> +				dmem=1G@5G
> +
> +	dmem=size[KMG]@addr[KMG]:align[KMG]
> +			[KNL] Ditto. 'align' should be power of two and it's

		Drop "it's"

> +			not smaller than the default alignment. Also 'size'
> +			and 'addr' must be aligned to 'align'. Specially,
> +			'@...r' and ':align' could occur in any order.
> +			Example: Exclude memory from 5G-6G for dmemfs.
> +				dmem=1G:1G@5G
> +
>  	driver_async_probe=  [KNL]
>  			List of driver names to be probed asynchronously.
>  			Format: <driver_name1>,<driver_name2>...


-- 
~Randy
Reported-by: Randy Dunlap <rdunlap@...radead.org>