diff mbox series

[v14,11/11] kdump: update Documentation about crashkernel

Message ID 20210130071025.65258-12-chenzhou10@huawei.com (mailing list archive)
State New, archived
Headers show
Series support reserving crashkernel above 4G on arm64 kdump | expand

Commit Message

chenzhou Jan. 30, 2021, 7:10 a.m. UTC 
For arm64, the behavior of crashkernel=X has been changed, which
tries low allocation in DMA zone and fall back to high allocation
if it fails.

We can also use "crashkernel=X,high" to select a high region above
DMA zone, which also tries to allocate at least 256M low memory in
DMA zone automatically and "crashkernel=Y,low" can be used to allocate
specified size low memory.

So update the Documentation.

Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
Tested-by: John Donnelly <John.p.donnelly@oracle.com>
---
 Documentation/admin-guide/kdump/kdump.rst     | 22 ++++++++++++++++---
 .../admin-guide/kernel-parameters.txt         | 11 ++++++++--
 2 files changed, 28 insertions(+), 5 deletions(-)

Comments

Randy Dunlap Jan. 30, 2021, 5:53 p.m. UTC | #1 
Hi--

On 1/29/21 11:10 PM, Chen Zhou wrote:
> ---
>  Documentation/admin-guide/kdump/kdump.rst     | 22 ++++++++++++++++---
>  .../admin-guide/kernel-parameters.txt         | 11 ++++++++--
>  2 files changed, 28 insertions(+), 5 deletions(-)
> 
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index a10b545c2070..908e5c8b61ba 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt

All of the "arm64" instances in [square brackets] should be "ARM64".

> @@ -738,6 +738,9 @@
>  			[KNL, X86-64] Select a region under 4G first, and
>  			fall back to reserve region above 4G when '@offset'
>  			hasn't been specified.
> +			[KNL, arm64] Try low allocation in DMA zone and fall back

			      here

> +			to high allocation if it fails when '@offset' hasn't been
> +			specified.
>  			See Documentation/admin-guide/kdump/kdump.rst for further details.
>  
>  	crashkernel=range1:size1[,range2:size2,...][@offset]
> @@ -754,6 +757,8 @@
>  			Otherwise memory region will be allocated below 4G, if
>  			available.
>  			It will be ignored if crashkernel=X is specified.
> +			[KNL, arm64] range in high memory.

			      here

> +			Allow kernel to allocate physical memory region from top.
>  	crashkernel=size[KMG],low
>  			[KNL, X86-64] range under 4G. When crashkernel=X,high
>  			is passed, kernel could allocate physical memory region
> @@ -762,13 +767,15 @@
>  			requires at least 64M+32K low memory, also enough extra
>  			low memory is needed to make sure DMA buffers for 32-bit
>  			devices won't run out. Kernel would try to allocate at
> -			at least 256M below 4G automatically.
> +			least 256M below 4G automatically.
>  			This one let user to specify own low range under 4G
>  			for second kernel instead.
>  			0: to disable low allocation.
>  			It will be ignored when crashkernel=X,high is not used
>  			or memory reserved is below 4G.
> -
> +			[KNL, arm64] range in low memory.

			      here

> +			This one let user to specify a low range in DMA zone for
> +			crash dump kernel.


Thanks.
chenzhou Feb. 4, 2021, 1:53 a.m. UTC | #2 
Hi Randy,


On 2021/1/31 1:53, Randy Dunlap wrote:
> Hi--
>
> On 1/29/21 11:10 PM, Chen Zhou wrote:
>> ---
>>  Documentation/admin-guide/kdump/kdump.rst     | 22 ++++++++++++++++---
>>  .../admin-guide/kernel-parameters.txt         | 11 ++++++++--
>>  2 files changed, 28 insertions(+), 5 deletions(-)
>>
>> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
>> index a10b545c2070..908e5c8b61ba 100644
>> --- a/Documentation/admin-guide/kernel-parameters.txt
>> +++ b/Documentation/admin-guide/kernel-parameters.txt
> All of the "arm64" instances in [square brackets] should be "ARM64".
Got it, thanks for your review.

Thanks,
Chen Zhou
>
>> @@ -738,6 +738,9 @@
>>  			[KNL, X86-64] Select a region under 4G first, and
>>  			fall back to reserve region above 4G when '@offset'
>>  			hasn't been specified.
>> +			[KNL, arm64] Try low allocation in DMA zone and fall back
> 			      here
>
>> +			to high allocation if it fails when '@offset' hasn't been
>> +			specified.
>>  			See Documentation/admin-guide/kdump/kdump.rst for further details.
>>  
>>  	crashkernel=range1:size1[,range2:size2,...][@offset]
>> @@ -754,6 +757,8 @@
>>  			Otherwise memory region will be allocated below 4G, if
>>  			available.
>>  			It will be ignored if crashkernel=X is specified.
>> +			[KNL, arm64] range in high memory.
> 			      here
>
>> +			Allow kernel to allocate physical memory region from top.
>>  	crashkernel=size[KMG],low
>>  			[KNL, X86-64] range under 4G. When crashkernel=X,high
>>  			is passed, kernel could allocate physical memory region
>> @@ -762,13 +767,15 @@
>>  			requires at least 64M+32K low memory, also enough extra
>>  			low memory is needed to make sure DMA buffers for 32-bit
>>  			devices won't run out. Kernel would try to allocate at
>> -			at least 256M below 4G automatically.
>> +			least 256M below 4G automatically.
>>  			This one let user to specify own low range under 4G
>>  			for second kernel instead.
>>  			0: to disable low allocation.
>>  			It will be ignored when crashkernel=X,high is not used
>>  			or memory reserved is below 4G.
>> -
>> +			[KNL, arm64] range in low memory.
> 			      here
>
>> +			This one let user to specify a low range in DMA zone for
>> +			crash dump kernel.
>
> Thanks.
>
Baoquan He Feb. 18, 2021, 8:40 a.m. UTC | #3 
On 01/30/21 at 03:10pm, Chen Zhou wrote:
> For arm64, the behavior of crashkernel=X has been changed, which
> tries low allocation in DMA zone and fall back to high allocation
> if it fails.
> 
> We can also use "crashkernel=X,high" to select a high region above
> DMA zone, which also tries to allocate at least 256M low memory in
> DMA zone automatically and "crashkernel=Y,low" can be used to allocate
> specified size low memory.
> 
> So update the Documentation.

Nice document adding which also takes care of x86 code implementation,
thanks. By the way, maybe you can remove John's 'Tested-by' since it
doesn't make much sense to test a document patch.

Acked-by: Baoquan He <bhe@redhat.com>

> 
> Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
> Tested-by: John Donnelly <John.p.donnelly@oracle.com>
> ---
>  Documentation/admin-guide/kdump/kdump.rst     | 22 ++++++++++++++++---
>  .../admin-guide/kernel-parameters.txt         | 11 ++++++++--
>  2 files changed, 28 insertions(+), 5 deletions(-)
> 
> diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admin-guide/kdump/kdump.rst
> index 75a9dd98e76e..0877c76f8015 100644
> --- a/Documentation/admin-guide/kdump/kdump.rst
> +++ b/Documentation/admin-guide/kdump/kdump.rst
> @@ -299,7 +299,16 @@ Boot into System Kernel
>     "crashkernel=64M@16M" tells the system kernel to reserve 64 MB of memory
>     starting at physical address 0x01000000 (16MB) for the dump-capture kernel.
>  
> -   On x86 and x86_64, use "crashkernel=64M@16M".
> +   On x86 use "crashkernel=64M@16M".
> +
> +   On x86_64, use "crashkernel=X" to select a region under 4G first, and
> +   fall back to reserve region above 4G. And go for high allocation
> +   directly if the required size is too large.
> +   We can also use "crashkernel=X,high" to select a region above 4G, which
> +   also tries to allocate at least 256M below 4G automatically and
> +   "crashkernel=Y,low" can be used to allocate specified size low memory.
> +   Use "crashkernel=Y@X" if you really have to reserve memory from specified
> +   start address X.
>  
>     On ppc64, use "crashkernel=128M@32M".
>  
> @@ -316,8 +325,15 @@ Boot into System Kernel
>     kernel will automatically locate the crash kernel image within the
>     first 512MB of RAM if X is not given.
>  
> -   On arm64, use "crashkernel=Y[@X]".  Note that the start address of
> -   the kernel, X if explicitly specified, must be aligned to 2MiB (0x200000).
> +   On arm64, use "crashkernel=X" to try low allocation in DMA zone and
> +   fall back to high allocation if it fails.
> +   We can also use "crashkernel=X,high" to select a high region above
> +   DMA zone, which also tries to allocate at least 256M low memory in
> +   DMA zone automatically.
> +   "crashkernel=Y,low" can be used to allocate specified size low memory.
> +   Use "crashkernel=Y@X" if you really have to reserve memory from
> +   specified start address X. Note that the start address of the kernel,
> +   X if explicitly specified, must be aligned to 2MiB (0x200000).
>  
>  Load the Dump-capture Kernel
>  ============================
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index a10b545c2070..908e5c8b61ba 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -738,6 +738,9 @@
>  			[KNL, X86-64] Select a region under 4G first, and
>  			fall back to reserve region above 4G when '@offset'
>  			hasn't been specified.
> +			[KNL, arm64] Try low allocation in DMA zone and fall back
> +			to high allocation if it fails when '@offset' hasn't been
> +			specified.
>  			See Documentation/admin-guide/kdump/kdump.rst for further details.
>  
>  	crashkernel=range1:size1[,range2:size2,...][@offset]
> @@ -754,6 +757,8 @@
>  			Otherwise memory region will be allocated below 4G, if
>  			available.
>  			It will be ignored if crashkernel=X is specified.
> +			[KNL, arm64] range in high memory.
> +			Allow kernel to allocate physical memory region from top.
>  	crashkernel=size[KMG],low
>  			[KNL, X86-64] range under 4G. When crashkernel=X,high
>  			is passed, kernel could allocate physical memory region
> @@ -762,13 +767,15 @@
>  			requires at least 64M+32K low memory, also enough extra
>  			low memory is needed to make sure DMA buffers for 32-bit
>  			devices won't run out. Kernel would try to allocate at
> -			at least 256M below 4G automatically.
> +			least 256M below 4G automatically.
>  			This one let user to specify own low range under 4G
>  			for second kernel instead.
>  			0: to disable low allocation.
>  			It will be ignored when crashkernel=X,high is not used
>  			or memory reserved is below 4G.
> -
> +			[KNL, arm64] range in low memory.
> +			This one let user to specify a low range in DMA zone for
> +			crash dump kernel.
>  	cryptomgr.notests
>  			[KNL] Disable crypto self-tests
>  
> -- 
> 2.20.1
>
chenzhou Feb. 20, 2021, 3:25 a.m. UTC | #4 
On 2021/2/18 16:40, Baoquan He wrote:
> On 01/30/21 at 03:10pm, Chen Zhou wrote:
>> For arm64, the behavior of crashkernel=X has been changed, which
>> tries low allocation in DMA zone and fall back to high allocation
>> if it fails.
>>
>> We can also use "crashkernel=X,high" to select a high region above
>> DMA zone, which also tries to allocate at least 256M low memory in
>> DMA zone automatically and "crashkernel=Y,low" can be used to allocate
>> specified size low memory.
>>
>> So update the Documentation.
> Nice document adding which also takes care of x86 code implementation,
> thanks. By the way, maybe you can remove John's 'Tested-by' since it
> doesn't make much sense to test a document patch.
I will remove the Tested-by in next version.
>
> Acked-by: Baoquan He <bhe@redhat.com>
>
>> Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
>> Tested-by: John Donnelly <John.p.donnelly@oracle.com>
>> ---
>>  Documentation/admin-guide/kdump/kdump.rst     | 22 ++++++++++++++++---
>>  .../admin-guide/kernel-parameters.txt         | 11 ++++++++--
>>  2 files changed, 28 insertions(+), 5 deletions(-)
>>
>> diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admin-guide/kdump/kdump.rst
>> index 75a9dd98e76e..0877c76f8015 100644
>> --- a/Documentation/admin-guide/kdump/kdump.rst
>> +++ b/Documentation/admin-guide/kdump/kdump.rst
>> @@ -299,7 +299,16 @@ Boot into System Kernel
>>     "crashkernel=64M@16M" tells the system kernel to reserve 64 MB of memory
>>     starting at physical address 0x01000000 (16MB) for the dump-capture kernel.
>>  
>> -   On x86 and x86_64, use "crashkernel=64M@16M".
>> +   On x86 use "crashkernel=64M@16M".
>> +
>> +   On x86_64, use "crashkernel=X" to select a region under 4G first, and
>> +   fall back to reserve region above 4G. And go for high allocation
>> +   directly if the required size is too large.
>> +   We can also use "crashkernel=X,high" to select a region above 4G, which
>> +   also tries to allocate at least 256M below 4G automatically and
>> +   "crashkernel=Y,low" can be used to allocate specified size low memory.
>> +   Use "crashkernel=Y@X" if you really have to reserve memory from specified
>> +   start address X.
>>  
>>     On ppc64, use "crashkernel=128M@32M".
>>  
>> @@ -316,8 +325,15 @@ Boot into System Kernel
>>     kernel will automatically locate the crash kernel image within the
>>     first 512MB of RAM if X is not given.
>>  
>> -   On arm64, use "crashkernel=Y[@X]".  Note that the start address of
>> -   the kernel, X if explicitly specified, must be aligned to 2MiB (0x200000).
>> +   On arm64, use "crashkernel=X" to try low allocation in DMA zone and
>> +   fall back to high allocation if it fails.
>> +   We can also use "crashkernel=X,high" to select a high region above
>> +   DMA zone, which also tries to allocate at least 256M low memory in
>> +   DMA zone automatically.
>> +   "crashkernel=Y,low" can be used to allocate specified size low memory.
>> +   Use "crashkernel=Y@X" if you really have to reserve memory from
>> +   specified start address X. Note that the start address of the kernel,
>> +   X if explicitly specified, must be aligned to 2MiB (0x200000).
>>  
>>  Load the Dump-capture Kernel
>>  ============================
>> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
>> index a10b545c2070..908e5c8b61ba 100644
>> --- a/Documentation/admin-guide/kernel-parameters.txt
>> +++ b/Documentation/admin-guide/kernel-parameters.txt
>> @@ -738,6 +738,9 @@
>>  			[KNL, X86-64] Select a region under 4G first, and
>>  			fall back to reserve region above 4G when '@offset'
>>  			hasn't been specified.
>> +			[KNL, arm64] Try low allocation in DMA zone and fall back
>> +			to high allocation if it fails when '@offset' hasn't been
>> +			specified.
>>  			See Documentation/admin-guide/kdump/kdump.rst for further details.
>>  
>>  	crashkernel=range1:size1[,range2:size2,...][@offset]
>> @@ -754,6 +757,8 @@
>>  			Otherwise memory region will be allocated below 4G, if
>>  			available.
>>  			It will be ignored if crashkernel=X is specified.
>> +			[KNL, arm64] range in high memory.
>> +			Allow kernel to allocate physical memory region from top.
>>  	crashkernel=size[KMG],low
>>  			[KNL, X86-64] range under 4G. When crashkernel=X,high
>>  			is passed, kernel could allocate physical memory region
>> @@ -762,13 +767,15 @@
>>  			requires at least 64M+32K low memory, also enough extra
>>  			low memory is needed to make sure DMA buffers for 32-bit
>>  			devices won't run out. Kernel would try to allocate at
>> -			at least 256M below 4G automatically.
>> +			least 256M below 4G automatically.
>>  			This one let user to specify own low range under 4G
>>  			for second kernel instead.
>>  			0: to disable low allocation.
>>  			It will be ignored when crashkernel=X,high is not used
>>  			or memory reserved is below 4G.
>> -
>> +			[KNL, arm64] range in low memory.
>> +			This one let user to specify a low range in DMA zone for
>> +			crash dump kernel.
>>  	cryptomgr.notests
>>  			[KNL] Disable crypto self-tests
>>  
>> -- 
>> 2.20.1
>>
> .
>
diff mbox series

Patch

diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admin-guide/kdump/kdump.rst
index 75a9dd98e76e..0877c76f8015 100644
--- a/Documentation/admin-guide/kdump/kdump.rst
+++ b/Documentation/admin-guide/kdump/kdump.rst
@@ -299,7 +299,16 @@  Boot into System Kernel
    "crashkernel=64M@16M" tells the system kernel to reserve 64 MB of memory
    starting at physical address 0x01000000 (16MB) for the dump-capture kernel.
 
-   On x86 and x86_64, use "crashkernel=64M@16M".
+   On x86 use "crashkernel=64M@16M".
+
+   On x86_64, use "crashkernel=X" to select a region under 4G first, and
+   fall back to reserve region above 4G. And go for high allocation
+   directly if the required size is too large.
+   We can also use "crashkernel=X,high" to select a region above 4G, which
+   also tries to allocate at least 256M below 4G automatically and
+   "crashkernel=Y,low" can be used to allocate specified size low memory.
+   Use "crashkernel=Y@X" if you really have to reserve memory from specified
+   start address X.
 
    On ppc64, use "crashkernel=128M@32M".
 
@@ -316,8 +325,15 @@  Boot into System Kernel
    kernel will automatically locate the crash kernel image within the
    first 512MB of RAM if X is not given.
 
-   On arm64, use "crashkernel=Y[@X]".  Note that the start address of
-   the kernel, X if explicitly specified, must be aligned to 2MiB (0x200000).
+   On arm64, use "crashkernel=X" to try low allocation in DMA zone and
+   fall back to high allocation if it fails.
+   We can also use "crashkernel=X,high" to select a high region above
+   DMA zone, which also tries to allocate at least 256M low memory in
+   DMA zone automatically.
+   "crashkernel=Y,low" can be used to allocate specified size low memory.
+   Use "crashkernel=Y@X" if you really have to reserve memory from
+   specified start address X. Note that the start address of the kernel,
+   X if explicitly specified, must be aligned to 2MiB (0x200000).
 
 Load the Dump-capture Kernel
 ============================
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index a10b545c2070..908e5c8b61ba 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -738,6 +738,9 @@ 
 			[KNL, X86-64] Select a region under 4G first, and
 			fall back to reserve region above 4G when '@offset'
 			hasn't been specified.
+			[KNL, arm64] Try low allocation in DMA zone and fall back
+			to high allocation if it fails when '@offset' hasn't been
+			specified.
 			See Documentation/admin-guide/kdump/kdump.rst for further details.
 
 	crashkernel=range1:size1[,range2:size2,...][@offset]
@@ -754,6 +757,8 @@ 
 			Otherwise memory region will be allocated below 4G, if
 			available.
 			It will be ignored if crashkernel=X is specified.
+			[KNL, arm64] range in high memory.
+			Allow kernel to allocate physical memory region from top.
 	crashkernel=size[KMG],low
 			[KNL, X86-64] range under 4G. When crashkernel=X,high
 			is passed, kernel could allocate physical memory region
@@ -762,13 +767,15 @@ 
 			requires at least 64M+32K low memory, also enough extra
 			low memory is needed to make sure DMA buffers for 32-bit
 			devices won't run out. Kernel would try to allocate at
-			at least 256M below 4G automatically.
+			least 256M below 4G automatically.
 			This one let user to specify own low range under 4G
 			for second kernel instead.
 			0: to disable low allocation.
 			It will be ignored when crashkernel=X,high is not used
 			or memory reserved is below 4G.
-
+			[KNL, arm64] range in low memory.
+			This one let user to specify a low range in DMA zone for
+			crash dump kernel.
 	cryptomgr.notests
 			[KNL] Disable crypto self-tests