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

From: Dou Liyang
Date: Sun Apr 23 2017 - 23:53:31 EST




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@xxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@xxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Cc: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx>
Cc: linux-doc@xxxxxxxxxxxxxxx
---
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.