[PATCH v3] Add arm description to Documentation/kdump/kdump.txt

[Vivek Goyal]

On Thu, Aug 14, 2014 at 05:55:32PM +0800, HuKeping wrote:
> ----------------------------------------
> 
> Add arm specific parts to kdump kernel documentation.
> 
> v2 -> v3
> - fix some spelling mistakes
> 
> Signed-off-by: Hu Keping <hukeping at huawei.com>
> ---

Acked-by: Vivek Goyal <vgoyal at redhat.com>

Vivek

>  Documentation/kdump/kdump.txt | 36 +++++++++++++++++++++++++++++++++---
>  1 file changed, 33 insertions(+), 3 deletions(-)
> 
> diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt
> index 9c7fd988..8c632db 100644
> --- a/Documentation/kdump/kdump.txt
> +++ b/Documentation/kdump/kdump.txt
> @@ -18,7 +18,7 @@ memory image to a dump file on the local disk, or across the network to
>  a remote system.
>  
>  Kdump and kexec are currently supported on the x86, x86_64, ppc64, ia64,
> -and s390x architectures.
> +s390x and arm architectures.
>  
>  When the system kernel boots, it reserves a small section of memory for
>  the dump-capture kernel. This ensures that ongoing Direct Memory Access
> @@ -119,7 +119,7 @@ There are two possible methods of using Kdump.
>  2) Or use the system kernel binary itself as dump-capture kernel and there is
>     no need to build a separate dump-capture kernel. This is possible
>     only with the architectures which support a relocatable kernel. As
> -   of today, i386, x86_64, ppc64 and ia64 architectures support relocatable
> +   of today, i386, x86_64, ppc64, ia64 and arm architectures support relocatable
>     kernel.
>  
>  Building a relocatable kernel is advantageous from the point of view that
> @@ -248,6 +248,13 @@ Dump-capture kernel config options (Arch Dependent, ia64)
>    kernel will be aligned to 64Mb, so if the start address is not then
>    any space below the alignment point will be wasted.
>  
> +Dump-capture kernel config options (Arch Dependent, arm)
> +----------------------------------------------------------
> +
> +-   To use a relocatable kernel,
> +    Enable "AUTO_ZRELADDR" support under "Boot" options:
> +
> +    AUTO_ZRELADDR=y
>  
>  Extended crashkernel syntax
>  ===========================
> @@ -263,6 +270,10 @@ The syntax is:
>      crashkernel=<range1>:<size1>[,<range2>:<size2>,...][@offset]
>      range=start-[end]
>  
> +Please note, on arm, the offset is required.
> +    crashkernel=<range1>:<size1>[,<range2>:<size2>,...]@offset
> +    range=start-[end]
> +
>      'start' is inclusive and 'end' is exclusive.
>  
>  For example:
> @@ -303,6 +314,12 @@ Boot into System Kernel
>     on the memory consumption of the kdump system. In general this is not
>     dependent on the memory size of the production system.
>  
> +   On arm, use "crashkernel=Y at X". Note that the start address of the kernel
> +   will be aligned to 128MiB (0x08000000), so if the start address is not then
> +   any space below the alignment point may be overwritten by the dump-capture kernel,
> +   which means it is possible that the vmcore is not that precise as expected.
> +
> +
>  Load the Dump-capture Kernel
>  ============================
>  
> @@ -322,7 +339,8 @@ For ia64:
>  	- Use vmlinux or vmlinuz.gz
>  For s390x:
>  	- Use image or bzImage
> -
> +For arm:
> +	- Use zImage
>  
>  If you are using a uncompressed vmlinux image then use following command
>  to load dump-capture kernel.
> @@ -338,6 +356,15 @@ to load dump-capture kernel.
>     --initrd=<initrd-for-dump-capture-kernel> \
>     --append="root=<root-dev> <arch-specific-options>"
>  
> +If you are using a compressed zImage, then use following command
> +to load dump-capture kernel.
> +
> +   kexec --type zImage -p <dump-capture-kernel-bzImage> \
> +   --initrd=<initrd-for-dump-capture-kernel> \
> +   --dtb=<dtb-for-dump-capture-kernel> \
> +   --append="root=<root-dev> <arch-specific-options>"
> +
> +
>  Please note, that --args-linux does not need to be specified for ia64.
>  It is planned to make this a no-op on that architecture, but for now
>  it should be omitted
> @@ -354,6 +381,9 @@ For ppc64:
>  For s390x:
>  	"1 maxcpus=1 cgroup_disable=memory"
>  
> +For arm:
> +	"1 maxcpus=1 reset_devices"
> +
>  Notes on loading the dump-capture kernel:
>  
>  * By default, the ELF headers are stored in ELF64 format to support
> -- 
> 1.8.5.5