Commit d67297ad authored by Mauro Carvalho Chehab's avatar Mauro Carvalho Chehab Committed by Jonathan Corbet
Browse files

docs: kdump: convert docs to ReST and rename to *.rst 



Convert kdump documentation to ReST and add it to the
user faced manual, as the documents are mainly focused on
sysadmins that would be enabling kdump.

Note: the vmcoreinfo.rst has one very long title on one of its
sub-sections:

	PG_lru|PG_private|PG_swapcache|PG_swapbacked|PG_slab|PG_hwpoision|PG_head_mask|PAGE_BUDDY_MAPCOUNT_VALUE(~PG_buddy)|PAGE_OFFLINE_MAPCOUNT_VALUE(~PG_offline)

I opted to break this one, into two entries with the same content,
in order to make it easier to display after being parsed in html and PDF.

The conversion is actually:
  - add blank lines and identation in order to identify paragraphs;
  - fix tables markups;
  - add some lists markups;
  - mark literal blocks;
  - adjust title markups.

At its new index.rst, let's add a :orphan: while this is not linked to
the main index.rst file, in order to avoid build warnings.

Signed-off-by: default avatarMauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: default avatarJonathan Corbet <corbet@lwn.net>
parent cd238eff

Documentation/admin-guide/bug-hunting.rst

+1 −1
Original line number Diff line number Diff line
@@ -90,7 +90,7 @@ the disk is not available then you have three options: 
    run a null modem to a second machine and capture the output there

    using your favourite communication program.  Minicom works well.



(3) Use Kdump (see Documentation/kdump/kdump.txt),

(3) Use Kdump (see Documentation/kdump/kdump.rst),

    extract the kernel ring buffer from old memory with using dmesg

    gdbmacro in Documentation/kdump/gdbmacros.txt.

Documentation/admin-guide/kernel-parameters.txt

+3 −3
Original line number Diff line number Diff line
@@ -708,14 +708,14 @@ 
			[KNL, x86_64] select a region under 4G first, and

			fall back to reserve region above 4G when '@offset'

			hasn't been specified.

			See Documentation/kdump/kdump.txt for further details.

			See Documentation/kdump/kdump.rst for further details.



	crashkernel=range1:size1[,range2:size2,...][@offset]

			[KNL] Same as above, but depends on the memory

			in the running system. The syntax of range is

			start-[end] where start and end are both

			a memory unit (amount[KMG]). See also

			Documentation/kdump/kdump.txt for an example.

			Documentation/kdump/kdump.rst for an example.



	crashkernel=size[KMG],high

			[KNL, x86_64] range could be above 4G. Allow kernel
@@ -1209,7 +1209,7 @@ 
			Specifies physical address of start of kernel core

			image elf header and optionally the size. Generally

			kexec loader will pass this option to capture kernel.

			See Documentation/kdump/kdump.txt for details.

			See Documentation/kdump/kdump.rst for details.



	enable_mtrr_cleanup [X86]

			The kernel tries to adjust MTRR layout from continuous

Documentation/kdump/index.rst

0 → 100644
+21 −0
Original line number Diff line number Diff line 
:orphan:



================================================================

Documentation for Kdump - The kexec-based Crash Dumping Solution

================================================================



This document includes overview, setup and installation, and analysis

information.



.. toctree::

    :maxdepth: 1



    kdump

    vmcoreinfo



.. only::  subproject and html



   Indices

   =======



   * :ref:`genindex`

Documentation/kdump/kdump.txt→Documentation/kdump/kdump.rst

+78 −53
Original line number Diff line number Diff line
@@ -71,9 +71,8 @@ This is a symlink to the latest version. 


The latest kexec-tools git tree is available at:



git://git.kernel.org/pub/scm/utils/kernel/kexec/kexec-tools.git

and

http://www.kernel.org/pub/scm/utils/kernel/kexec/kexec-tools.git

- git://git.kernel.org/pub/scm/utils/kernel/kexec/kexec-tools.git

- http://www.kernel.org/pub/scm/utils/kernel/kexec/kexec-tools.git



There is also a gitweb interface available at

http://www.kernel.org/git/?p=utils/kernel/kexec/kexec-tools.git
@@ -81,23 +80,23 @@ http://www.kernel.org/git/?p=utils/kernel/kexec/kexec-tools.git 
More information about kexec-tools can be found at

http://horms.net/projects/kexec/



3) Unpack the tarball with the tar command, as follows:

3) Unpack the tarball with the tar command, as follows::



	tar xvpzf kexec-tools.tar.gz



4) Change to the kexec-tools directory, as follows:

4) Change to the kexec-tools directory, as follows::



	cd kexec-tools-VERSION



5) Configure the package, as follows:

5) Configure the package, as follows::



	./configure



6) Compile the package, as follows:

6) Compile the package, as follows::



	make



7) Install the package, as follows:

7) Install the package, as follows::



	make install
@@ -126,23 +125,23 @@ dump-capture kernels for enabling kdump support. 
System kernel config options

----------------------------



1) Enable "kexec system call" in "Processor type and features."

1) Enable "kexec system call" in "Processor type and features."::



	CONFIG_KEXEC=y



2) Enable "sysfs file system support" in "Filesystem" -> "Pseudo

   filesystems." This is usually enabled by default.

   filesystems." This is usually enabled by default::



	CONFIG_SYSFS=y



   Note that "sysfs file system support" might not appear in the "Pseudo

   filesystems" menu if "Configure standard kernel features (for small

   systems)" is not enabled in "General Setup." In this case, check the

   .config file itself to ensure that sysfs is turned on, as follows:

   .config file itself to ensure that sysfs is turned on, as follows::



	grep 'CONFIG_SYSFS' .config



3) Enable "Compile the kernel with debug info" in "Kernel hacking."

3) Enable "Compile the kernel with debug info" in "Kernel hacking."::



	CONFIG_DEBUG_INFO=Y
@@ -154,27 +153,30 @@ Dump-capture kernel config options (Arch Independent) 
-----------------------------------------------------



1) Enable "kernel crash dumps" support under "Processor type and

   features":

   features"::



	CONFIG_CRASH_DUMP=y



2) Enable "/proc/vmcore support" under "Filesystems" -> "Pseudo filesystems".

2) Enable "/proc/vmcore support" under "Filesystems" -> "Pseudo filesystems"::



	CONFIG_PROC_VMCORE=y



   (CONFIG_PROC_VMCORE is set by default when CONFIG_CRASH_DUMP is selected.)



Dump-capture kernel config options (Arch Dependent, i386 and x86_64)

--------------------------------------------------------------------



1) On i386, enable high memory support under "Processor type and

   features":

   features"::



	CONFIG_HIGHMEM64G=y

   or



   or::



	CONFIG_HIGHMEM4G



2) On i386 and x86_64, disable symmetric multi-processing support

   under "Processor type and features":

   under "Processor type and features"::



	CONFIG_SMP=n
@@ -184,7 +186,7 @@ Dump-capture kernel config options (Arch Dependent, i386 and x86_64) 


3) If one wants to build and use a relocatable kernel,

   Enable "Build a relocatable kernel" support under "Processor type and

   features"

   features"::



	CONFIG_RELOCATABLE=y
@@ -211,11 +213,11 @@ Dump-capture kernel config options (Arch Dependent, i386 and x86_64) 
Dump-capture kernel config options (Arch Dependent, ppc64)

----------------------------------------------------------



1) Enable "Build a kdump crash kernel" support under "Kernel" options:

1) Enable "Build a kdump crash kernel" support under "Kernel" options::



	CONFIG_CRASH_DUMP=y



2)   Enable "Build a relocatable kernel" support

2)   Enable "Build a relocatable kernel" support::



	CONFIG_RELOCATABLE=y
@@ -231,10 +233,12 @@ Dump-capture kernel config options (Arch Dependent, ia64) 


  The crashkernel region can be automatically placed by the system

  kernel at run time. This is done by specifying the base address as 0,

  or omitting it all together.

  or omitting it all together::



	crashkernel=256M@0

  or



  or::



	crashkernel=256M



  If the start address is specified, note that the start address of the
@@ -245,7 +249,7 @@ Dump-capture kernel config options (Arch Dependent, arm) 
----------------------------------------------------------



-   To use a relocatable kernel,

    Enable "AUTO_ZRELADDR" support under "Boot" options:

    Enable "AUTO_ZRELADDR" support under "Boot" options::



	AUTO_ZRELADDR=y
@@ -265,12 +269,12 @@ on the value of System RAM -- that's mostly for distributors that pre-setup 
the kernel command line to avoid a unbootable system after some memory has

been removed from the machine.



The syntax is:

The syntax is::



    crashkernel=<range1>:<size1>[,<range2>:<size2>,...][@offset]

    range=start-[end]



For example:

For example::



    crashkernel=512M-2G:64M,2G-:128M
@@ -326,35 +330,46 @@ can choose to load the uncompressed vmlinux or compressed bzImage/vmlinuz 
of dump-capture kernel. Following is the summary.



For i386 and x86_64:



	- Use vmlinux if kernel is not relocatable.

	- Use bzImage/vmlinuz if kernel is relocatable.



For ppc64:



	- Use vmlinux



For ia64:



	- Use vmlinux or vmlinuz.gz



For s390x:



	- Use image or bzImage



For arm:



	- Use zImage



For arm64:



	- Use vmlinux or Image



If you are using an uncompressed vmlinux image then use following command

to load dump-capture kernel.

to load dump-capture kernel::



   kexec -p <dump-capture-kernel-vmlinux-image> \

   --initrd=<initrd-for-dump-capture-kernel> --args-linux \

   --append="root=<root-dev> <arch-specific-options>"



If you are using a compressed bzImage/vmlinuz, then use following command

to load dump-capture kernel.

to load dump-capture kernel::



   kexec -p <dump-capture-kernel-bzImage> \

   --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.

to load dump-capture kernel::



   kexec --type zImage -p <dump-capture-kernel-bzImage> \

   --initrd=<initrd-for-dump-capture-kernel> \
@@ -362,7 +377,7 @@ to load dump-capture kernel. 
   --append="root=<root-dev> <arch-specific-options>"



If you are using an uncompressed Image, then use following command

to load dump-capture kernel.

to load dump-capture kernel::



   kexec -p <dump-capture-kernel-Image> \

   --initrd=<initrd-for-dump-capture-kernel> \
@@ -376,18 +391,23 @@ Following are the arch specific command line options to be used while 
loading dump-capture kernel.



For i386, x86_64 and ia64:



	"1 irqpoll maxcpus=1 reset_devices"



For ppc64:



	"1 maxcpus=1 noirqdistrib reset_devices"



For s390x:



	"1 maxcpus=1 cgroup_disable=memory"



For arm:



	"1 maxcpus=1 reset_devices"



For arm64:



	"1 maxcpus=1 reset_devices"



Notes on loading the dump-capture kernel:
@@ -464,7 +484,7 @@ Write Out the Dump File 
=======================



After the dump-capture kernel is booted, write out the dump file with

the following command:

the following command::



   cp /proc/vmcore <dump-file>
@@ -476,7 +496,7 @@ Before analyzing the dump image, you should reboot into a stable kernel. 


You can do limited analysis using GDB on the dump file copied out of

/proc/vmcore. Use the debug vmlinux built with -g and run the following

command:

command::



   gdb vmlinux <dump-file>
@@ -504,6 +524,11 @@ to achieve the same behaviour. 
Contact

=======



Vivek Goyal (vgoyal@redhat.com)

Maneesh Soni (maneesh@in.ibm.com)

- Vivek Goyal (vgoyal@redhat.com)

- Maneesh Soni (maneesh@in.ibm.com)



GDB macros

==========



.. include:: gdbmacros.txt

   :literal:

Documentation/kdump/vmcoreinfo.txt→Documentation/kdump/vmcoreinfo.rst

+26 −33
Original line number Diff line number Diff line 
================================================================

==========

VMCOREINFO

================================================================

==========



===========

What is it?

===========
@@ -12,7 +11,6 @@ values, field offsets, etc. These data are packed into an ELF note 
section and used by user-space tools like crash and makedumpfile to

analyze a kernel's memory layout.



================

Common variables

================
@@ -49,7 +47,7 @@ in a system, one bit position per node number. Used to keep track of 
which nodes are in the system and online.



swapper_pg_dir

-------------

--------------



The global page directory pointer of the kernel. Used to translate

virtual to physical addresses.
@@ -132,16 +130,14 @@ nodemask_t 
The size of a nodemask_t type. Used to compute the number of online

nodes.



(page, flags|_refcount|mapping|lru|_mapcount|private|compound_dtor|

       compound_order|compound_head)

-------------------------------------------------------------------

(page, flags|_refcount|mapping|lru|_mapcount|private|compound_dtor|compound_order|compound_head)

-------------------------------------------------------------------------------------------------



User-space tools compute their values based on the offset of these

variables. The variables are used when excluding unnecessary pages.



(pglist_data, node_zones|nr_zones|node_mem_map|node_start_pfn|node_

              spanned_pages|node_id)

-------------------------------------------------------------------

(pglist_data, node_zones|nr_zones|node_mem_map|node_start_pfn|node_spanned_pages|node_id)

-----------------------------------------------------------------------------------------



On NUMA machines, each NUMA node has a pg_data_t to describe its memory

layout. On UMA machines there is a single pglist_data which describes the
@@ -245,21 +241,25 @@ NR_FREE_PAGES 
On linux-2.6.21 or later, the number of free pages is in

vm_stat[NR_FREE_PAGES]. Used to get the number of free pages.



PG_lru|PG_private|PG_swapcache|PG_swapbacked|PG_slab|PG_hwpoision

|PG_head_mask|PAGE_BUDDY_MAPCOUNT_VALUE(~PG_buddy)

|PAGE_OFFLINE_MAPCOUNT_VALUE(~PG_offline)

-----------------------------------------------------------------

PG_lru|PG_private|PG_swapcache|PG_swapbacked|PG_slab|PG_hwpoision|PG_head_mask

------------------------------------------------------------------------------



Page attributes. These flags are used to filter various unnecessary for

dumping pages.



PAGE_BUDDY_MAPCOUNT_VALUE(~PG_buddy)|PAGE_OFFLINE_MAPCOUNT_VALUE(~PG_offline)

-----------------------------------------------------------------------------



More page attributes. These flags are used to filter various unnecessary for

dumping pages.





HUGETLB_PAGE_DTOR

-----------------



The HUGETLB_PAGE_DTOR flag denotes hugetlbfs pages. Makedumpfile

excludes these pages.



======

x86_64

======
@@ -318,12 +318,12 @@ address. 
Currently, sme_mask stores the value of the C-bit position. If needed,

additional SME-relevant info can be placed in that variable.



For example:

For example::



  [ misc	        ][ enc bit  ][ other misc SME info       ]

  0000_0000_0000_0000_1000_0000_0000_0000_0000_0000_..._0000

  63   59   55   51   47   43   39   35   31   27   ... 3



======

x86_32

======
@@ -335,7 +335,6 @@ of a higher page table lookup overhead, and also consumes more page 
table space per process. Used to check whether PAE was enabled in the

crash kernel when converting virtual addresses to physical addresses.



====

ia64

====
@@ -366,7 +365,6 @@ PGTABLE_3|PGTABLE_4 
User-space tools need to know whether the crash kernel was in 3-level or

4-level paging mode. Used to distinguish the page table.



=====

ARM64

=====
@@ -395,9 +393,8 @@ KERNELOFFSET 
The kernel randomization offset. Used to compute the page offset. If

KASLR is disabled, this value is zero.



====

arm

====

===



ARM_LPAE

--------
@@ -405,12 +402,11 @@ ARM_LPAE 
It indicates whether the crash kernel supports large physical address

extensions. Used to translate virtual to physical addresses.



====

s390

====



lowcore_ptr

----------

-----------



An array with a pointer to the lowcore of every CPU. Used to print the

psw and all registers information.
@@ -425,7 +421,6 @@ Used to get the vmalloc_start address from the high_memory symbol. 


The maximum number of CPUs.



=======

powerpc

=======
@@ -460,9 +455,8 @@ Page size definitions, i.e. 4k, 64k, or 16M. 


Used to make vtop translations.



vmemmap_backing|(vmemmap_backing, list)|(vmemmap_backing, phys)|

(vmemmap_backing, virt_addr)

----------------------------------------------------------------

vmemmap_backing|(vmemmap_backing, list)|(vmemmap_backing, phys)|(vmemmap_backing, virt_addr)

--------------------------------------------------------------------------------------------



The vmemmap virtual address space management does not have a traditional

page table to track which virtual struct pages are backed by a physical
@@ -480,7 +474,6 @@ member. 


Used in vtop translations.



==

sh

==

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