diff mbox

[v12,14/16] arm64: kdump: update a kernel doc

Message ID 3c9bfb1df9bba481b753d8d630e4e3d45f986f04.1448403503.git.geoff@infradead.org
State Superseded
Headers show

Commit Message

Geoff Levand Nov. 24, 2015, 10:25 p.m. UTC
From: AKASHI Takahiro <takahiro.akashi@linaro.org>


This patch adds arch specific descriptions about kdump usage on arm64
to kdump.txt.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>

---
 Documentation/kdump/kdump.txt | 32 +++++++++++++++++++++++++++++++-
 1 file changed, 31 insertions(+), 1 deletion(-)

-- 
2.5.0



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Comments

Will Deacon Dec. 15, 2015, 5:17 p.m. UTC | #1
On Tue, Nov 24, 2015 at 10:25:34PM +0000, Geoff Levand wrote:
> From: AKASHI Takahiro <takahiro.akashi@linaro.org>

> 

> This patch adds arch specific descriptions about kdump usage on arm64

> to kdump.txt.

> 

> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>

> ---

>  Documentation/kdump/kdump.txt | 32 +++++++++++++++++++++++++++++++-

>  1 file changed, 31 insertions(+), 1 deletion(-)

> 

> diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt

> index bc4bd5a..7d3fad0 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,

> -s390x and arm architectures.

> +s390x, arm and arm64 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

> @@ -249,6 +249,29 @@ Dump-capture kernel config options (Arch Dependent, arm)

>  

>      AUTO_ZRELADDR=y

>  

> +Dump-capture kernel config options (Arch Dependent, arm64)

> +----------------------------------------------------------

> +

> +1) Disable symmetric multi-processing support under "Processor type and

> +   features":

> +

> +   CONFIG_SMP=n

> +

> +   (If CONFIG_SMP=y, then specify maxcpus=1 on the kernel command line

> +   when loading the dump-capture kernel, see section "Load the Dump-capture

> +   Kernel".)


SMP is now forced on, so please update this text.

> +2) The maximum memory size on the dump-capture kernel must be limited by

> +   specifying:

> +

> +   mem=X[MG]

> +

> +   where X should be less than or equal to the size in "crashkernel="

> +   boot parameter. Kexec-tools will automatically add this.

> +

> +3) Currently, kvm will not be enabled on the dump-capture kernel even

> +   if it is configured.

> +

>  Extended crashkernel syntax

>  ===========================

>  

> @@ -312,6 +335,8 @@ Boot into System Kernel

>     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.

>  

> +   On arm64, use "crashkernel=Y[@X]".  Note that the start address of

> +   the kernel, X if explicitly specified, must be aligned to 2MiB (0x200000).

>  

>  Load the Dump-capture Kernel

>  ============================

> @@ -334,6 +359,8 @@ For s390x:

>  	- Use image or bzImage

>  For arm:

>  	- Use zImage

> +For arm64:

> +	- Use vmlinux


What? Why doesn't Image work?

Will

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AKASHI Takahiro Dec. 16, 2015, 5:48 a.m. UTC | #2
On 12/16/2015 02:17 AM, Will Deacon wrote:
> On Tue, Nov 24, 2015 at 10:25:34PM +0000, Geoff Levand wrote:

>> From: AKASHI Takahiro <takahiro.akashi@linaro.org>

>>

>> This patch adds arch specific descriptions about kdump usage on arm64

>> to kdump.txt.

>>

>> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>

>> ---

>>   Documentation/kdump/kdump.txt | 32 +++++++++++++++++++++++++++++++-

>>   1 file changed, 31 insertions(+), 1 deletion(-)

>>

>> diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt

>> index bc4bd5a..7d3fad0 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,

>> -s390x and arm architectures.

>> +s390x, arm and arm64 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

>> @@ -249,6 +249,29 @@ Dump-capture kernel config options (Arch Dependent, arm)

>>

>>       AUTO_ZRELADDR=y

>>

>> +Dump-capture kernel config options (Arch Dependent, arm64)

>> +----------------------------------------------------------

>> +

>> +1) Disable symmetric multi-processing support under "Processor type and

>> +   features":

>> +

>> +   CONFIG_SMP=n

>> +

>> +   (If CONFIG_SMP=y, then specify maxcpus=1 on the kernel command line

>> +   when loading the dump-capture kernel, see section "Load the Dump-capture

>> +   Kernel".)

>

> SMP is now forced on, so please update this text.


OK, I will fix it.

>> +2) The maximum memory size on the dump-capture kernel must be limited by

>> +   specifying:

>> +

>> +   mem=X[MG]

>> +

>> +   where X should be less than or equal to the size in "crashkernel="

>> +   boot parameter. Kexec-tools will automatically add this.

>> +

>> +3) Currently, kvm will not be enabled on the dump-capture kernel even

>> +   if it is configured.

>> +

>>   Extended crashkernel syntax

>>   ===========================

>>

>> @@ -312,6 +335,8 @@ Boot into System Kernel

>>      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.

>>

>> +   On arm64, use "crashkernel=Y[@X]".  Note that the start address of

>> +   the kernel, X if explicitly specified, must be aligned to 2MiB (0x200000).

>>

>>   Load the Dump-capture Kernel

>>   ============================

>> @@ -334,6 +359,8 @@ For s390x:

>>   	- Use image or bzImage

>>   For arm:

>>   	- Use zImage

>> +For arm64:

>> +	- Use vmlinux

>

> What? Why doesn't Image work?


Actually it depends on kexec-tools, not the kernel.
Initially Geoff implemented vmlinux support only, then
recently Pratyush (RedHat) gave us a patch for "Image" support.

So now Image should work.

-Takahiro AKASHI

> Will

>


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diff mbox

Patch

diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt
index bc4bd5a..7d3fad0 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,
-s390x and arm architectures.
+s390x, arm and arm64 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
@@ -249,6 +249,29 @@  Dump-capture kernel config options (Arch Dependent, arm)
 
     AUTO_ZRELADDR=y
 
+Dump-capture kernel config options (Arch Dependent, arm64)
+----------------------------------------------------------
+
+1) Disable symmetric multi-processing support under "Processor type and
+   features":
+
+   CONFIG_SMP=n
+
+   (If CONFIG_SMP=y, then specify maxcpus=1 on the kernel command line
+   when loading the dump-capture kernel, see section "Load the Dump-capture
+   Kernel".)
+
+2) The maximum memory size on the dump-capture kernel must be limited by
+   specifying:
+
+   mem=X[MG]
+
+   where X should be less than or equal to the size in "crashkernel="
+   boot parameter. Kexec-tools will automatically add this.
+
+3) Currently, kvm will not be enabled on the dump-capture kernel even
+   if it is configured.
+
 Extended crashkernel syntax
 ===========================
 
@@ -312,6 +335,8 @@  Boot into System Kernel
    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.
 
+   On arm64, use "crashkernel=Y[@X]".  Note that the start address of
+   the kernel, X if explicitly specified, must be aligned to 2MiB (0x200000).
 
 Load the Dump-capture Kernel
 ============================
@@ -334,6 +359,8 @@  For s390x:
 	- Use image or bzImage
 For arm:
 	- Use zImage
+For arm64:
+	- Use vmlinux
 
 If you are using a uncompressed vmlinux image then use following command
 to load dump-capture kernel.
@@ -377,6 +404,9 @@  For s390x:
 For arm:
 	"1 maxcpus=1 reset_devices"
 
+For arm64:
+	"1 mem=X[MG] maxcpus=1 reset_devices"
+
 Notes on loading the dump-capture kernel:
 
 * By default, the ELF headers are stored in ELF64 format to support