linux-kernel - Re: [PATCH v2 3/3] Documentation/kernel-parameters.txt: Update 'memmap=' option description

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Message-ID: <9ee7e238-3baf-332a-e77a-ea5ed8d9416b@cn.fujitsu.com>
Date:   Mon, 24 Apr 2017 11:53:07 +0800
From:   Dou Liyang <douly.fnst@...fujitsu.com>
To:     Baoquan He <bhe@...hat.com>, <linux-kernel@...r.kernel.org>,
        <keescook@...omium.org>, <mingo@...nel.org>
CC:     <dave.jiang@...el.com>, <dan.j.williams@...el.com>,
        <hpa@...or.com>, <tglx@...utronix.de>, <dyoung@...hat.com>,
        Jonathan Corbet <corbet@....net>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        <linux-doc@...r.kernel.org>
Subject: Re: [PATCH v2 3/3] Documentation/kernel-parameters.txt: Update
 'memmap=' option description



At 04/24/2017 10:40 AM, Baoquan He wrote:
> In commit:
>
>   9710f581bb4c ("x86, mm: Let "memmap=" take more entries one time")
>
> ... 'memmap=' was changed to adopt multiple, comma delimited values in a
> single entry, so update the related description.
>
> In the special case of only specifying size value without an offset,
> like memmap=nn[KMG], memmap behaves similarly to mem=nn[KMG], so update
> it too here.
>
> Furthermore, for memmap=nn[KMG]$ss[KMG], an escape character needs be added
> before '$' for some bootloaders. E.g in grub2, if we specify memmap=100M$5G
> as suggested by the documentation, "memmap=100MG" gets passed to the kernel.
>
> Clarify all this.
>
> Signed-off-by: Baoquan He <bhe@...hat.com>
> Cc: Jonathan Corbet <corbet@....net>
> Cc: "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Cc: Bjorn Helgaas <bhelgaas@...gle.com>
> Cc: Mauro Carvalho Chehab <mchehab@...nel.org>
> Cc: linux-doc@...r.kernel.org
> ---
>  Documentation/admin-guide/kernel-parameters.txt | 9 +++++++++
>  1 file changed, 9 insertions(+)
>
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 986e443..4054328 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -2097,6 +2097,12 @@
>  	memmap=nn[KMG]@ss[KMG]
>  			[KNL] Force usage of a specific region of memory.
>  			Region of memory to be used is from ss to ss+nn.
> +			If @ss[KMG] is ommited, it equals to mem=nn[KMG]

s/ommited/omitted/

Thanks,
	Liyang
> +			which limits max address as nn[KMG].
> +			Multiple different options can be put into one entry
> +			with comma delimited to save space:
> +			Example:
> +				memmap=100M@2G,100M#3G,1G!1024G
>
>  	memmap=nn[KMG]#ss[KMG]
>  			[KNL,ACPI] Mark specific memory as ACPI data.
> @@ -2109,6 +2115,9 @@
>  			         memmap=64K$0x18690000
>  			         or
>  			         memmap=0x10000$0x18690000
> +			Some bootloaders may need escape character before '$',
> +			like in grub2, otherwise '$' and the following number
> +			will be eaten.
>
>  	memmap=nn[KMG]!ss[KMG]
>  			[KNL,X86] Mark specific memory as protected.
>