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Diffstat (limited to 'Documentation/admin-guide/kdump/kdump.rst')
| -rw-r--r-- | Documentation/admin-guide/kdump/kdump.rst | 111 |
1 files changed, 63 insertions, 48 deletions
diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admin-guide/kdump/kdump.rst index a748e7eb4429..7b011eb116a7 100644 --- a/Documentation/admin-guide/kdump/kdump.rst +++ b/Documentation/admin-guide/kdump/kdump.rst @@ -17,7 +17,7 @@ You can use common commands, such as cp, scp or makedumpfile to copy the 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, +Kdump and kexec are currently supported on the x86, x86_64, ppc64, s390x, arm and arm64 architectures. When the system kernel boots, it reserves a small section of memory for @@ -113,7 +113,7 @@ 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, ia64, arm and arm64 architectures support + of today, i386, x86_64, ppc64, arm and arm64 architectures support relocatable kernel. Building a relocatable kernel is advantageous from the point of view that @@ -136,10 +136,6 @@ System kernel config options CONFIG_KEXEC_CORE=y - Subsequently, CRASH_CORE is selected by KEXEC_CORE:: - - CONFIG_CRASH_CORE=y - 2) Enable "sysfs file system support" in "Filesystem" -> "Pseudo filesystems." This is usually enabled by default:: @@ -168,6 +164,10 @@ Dump-capture kernel config options (Arch Independent) CONFIG_CRASH_DUMP=y + And this will select VMCORE_INFO and CRASH_RESERVE:: + CONFIG_VMCORE_INFO=y + CONFIG_CRASH_RESERVE=y + 2) Enable "/proc/vmcore support" under "Filesystems" -> "Pseudo filesystems":: CONFIG_PROC_VMCORE=y @@ -180,10 +180,6 @@ Dump-capture kernel config options (Arch Dependent, i386 and x86_64) 1) On i386, enable high memory support under "Processor type and features":: - CONFIG_HIGHMEM64G=y - - or:: - CONFIG_HIGHMEM4G 2) With CONFIG_SMP=y, usually nr_cpus=1 need specified on the kernel @@ -191,9 +187,7 @@ Dump-capture kernel config options (Arch Dependent, i386 and x86_64) CPU is enough for kdump kernel to dump vmcore on most of systems. However, you can also specify nr_cpus=X to enable multiple processors - in kdump kernel. In this case, "disable_cpu_apicid=" is needed to - tell kdump kernel which cpu is 1st kernel's BSP. Please refer to - admin-guide/kernel-parameters.txt for more details. + in kdump kernel. With CONFIG_SMP=n, the above things are not related. @@ -236,24 +230,6 @@ Dump-capture kernel config options (Arch Dependent, ppc64) Make and install the kernel and its modules. -Dump-capture kernel config options (Arch Dependent, ia64) ----------------------------------------------------------- - -- No specific options are required to create a dump-capture kernel - for ia64, other than those specified in the arch independent section - above. This means that it is possible to use the system kernel - as a dump-capture kernel if desired. - - The crashkernel region can be automatically placed by the system - kernel at runtime. This is done by specifying the base address as 0, - or omitting it all together:: - - crashkernel=256M@0 - - or:: - - crashkernel=256M - Dump-capture kernel config options (Arch Dependent, arm) ---------------------------------------------------------- @@ -335,6 +311,27 @@ crashkernel syntax crashkernel=0,low +4) crashkernel=size,cma + + Reserve additional crash kernel memory from CMA. This reservation is + usable by the first system's userspace memory and kernel movable + allocations (memory balloon, zswap). Pages allocated from this memory + range will not be included in the vmcore so this should not be used if + dumping of userspace memory is intended and it has to be expected that + some movable kernel pages may be missing from the dump. + + A standard crashkernel reservation, as described above, is still needed + to hold the crash kernel and initrd. + + This option increases the risk of a kdump failure: DMA transfers + configured by the first kernel may end up corrupting the second + kernel's memory. + + This reservation method is intended for systems that can't afford to + sacrifice enough memory for standard crashkernel reservation and where + less reliable and possibly incomplete kdump is preferable to no kdump at + all. + Boot into System Kernel ----------------------- 1) Update the boot loader (such as grub, yaboot, or lilo) configuration @@ -348,11 +345,6 @@ Boot into System Kernel On ppc64, use "crashkernel=128M@32M". - On ia64, 256M@256M is a generous value that typically works. - The region may be automatically placed on ia64, see the - dump-capture kernel config option notes above. - If use sparse memory, the size should be rounded to GRANULE boundaries. - On s390x, typically use "crashkernel=xxM". The value of xx is dependent on the memory consumption of the kdump system. In general this is not dependent on the memory size of the production system. @@ -383,10 +375,6 @@ For ppc64: - Use vmlinux -For ia64: - - - Use vmlinux or vmlinuz.gz - For s390x: - Use image or bzImage @@ -428,14 +416,10 @@ to load dump-capture kernel:: --initrd=<initrd-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 - Following are the arch specific command line options to be used while loading dump-capture kernel. -For i386, x86_64 and ia64: +For i386 and x86_64: "1 irqpoll nr_cpus=1 reset_devices" @@ -485,10 +469,9 @@ Notes on loading the dump-capture kernel: to use multi-thread programs with it, such as parallel dump feature of makedumpfile. Otherwise, the multi-thread program may have a great performance degradation. To enable multi-cpu support, you should bring up an - SMP dump-capture kernel and specify maxcpus/nr_cpus, disable_cpu_apicid=[X] - options while loading it. + SMP dump-capture kernel and specify maxcpus/nr_cpus options while loading it. -* For s390x there are two kdump modes: If a ELF header is specified with +* For s390x there are two kdump modes: If an ELF header is specified with the elfcorehdr= kernel parameter, it is used by the kdump kernel as it is done on all other architectures. If no elfcorehdr= kernel parameter is specified, the s390x kdump kernel dynamically creates the header. The @@ -585,6 +568,38 @@ from within add_taint() whenever the value set in this bitmask matches with the bit flag being set by add_taint(). This will cause a kdump to occur at the add_taint()->panic() call. +Write the dump file to encrypted disk volume +============================================ + +CONFIG_CRASH_DM_CRYPT can be enabled to support saving the dump file to an +encrypted disk volume (only x86_64 supported for now). User space can interact +with /sys/kernel/config/crash_dm_crypt_keys for setup, + +1. Tell the first kernel what logon keys are needed to unlock the disk volumes, + # Add key #1 + mkdir /sys/kernel/config/crash_dm_crypt_keys/7d26b7b4-e342-4d2d-b660-7426b0996720 + # Add key #1's description + echo cryptsetup:7d26b7b4-e342-4d2d-b660-7426b0996720 > /sys/kernel/config/crash_dm_crypt_keys/description + + # how many keys do we have now? + cat /sys/kernel/config/crash_dm_crypt_keys/count + 1 + + # Add key #2 in the same way + + # how many keys do we have now? + cat /sys/kernel/config/crash_dm_crypt_keys/count + 2 + + # To support CPU/memory hot-plugging, re-use keys already saved to reserved + # memory + echo true > /sys/kernel/config/crash_dm_crypt_key/reuse + +2. Load the dump-capture kernel + +3. After the dump-capture kerne get booted, restore the keys to user keyring + echo yes > /sys/kernel/crash_dm_crypt_keys/restore + Contact ======= |