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

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Date:   Mon, 24 Apr 2017 14:54:33 +0800
From:   Baoquan He <bhe@...hat.com>
To:     Dou Liyang <douly.fnst@...fujitsu.com>
Cc:     linux-kernel@...r.kernel.org, keescook@...omium.org,
        mingo@...nel.org, 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

On 04/24/17 at 11:53am, Dou Liyang wrote:
> 
> 
> 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/

Right, thanks. Will see if there's other comment and update.

> 
> > +			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.
> > 
> 
>