Lines Matching refs:kernel
11 Kdump uses kexec to quickly boot to a dump-capture kernel whenever a
12 dump of the system kernel's memory needs to be taken (for example, when
13 the system panics). The system kernel's memory image is preserved across
14 the reboot and is accessible to the dump-capture kernel.
23 When the system kernel boots, it reserves a small section of memory for
24 the dump-capture kernel. This ensures that ongoing Direct Memory Access
25 (DMA) from the system kernel does not corrupt the dump-capture kernel.
26 The kexec -p command loads the dump-capture kernel into this reserved
30 regardless of where the kernel loads. For simpler handling, the whole
31 low 1M is reserved to avoid any later kernel or device driver writing
33 by kdump kernel without extra handling.
36 regardless of where the kernel is loaded and to support 64K page size
40 with the region [0, crashkernel region size] and then the kdump kernel
41 runs in [0, crashkernel region size]. Therefore no relocatable kernel is
44 All of the necessary information about the system kernel's core image is
47 passed to the dump-capture kernel through the elfcorehdr= boot
51 With the dump-capture kernel, you can access the memory image through
55 options, e.g with '-d 31' it will only write out kernel data. Further,
70 http://kernel.org/pub/linux/utils/kernel/kexec/kexec-tools.tar.gz
76 - git://git.kernel.org/pub/scm/utils/kernel/kexec/kexec-tools.git
77 - http://www.kernel.org/pub/scm/utils/kernel/kexec/kexec-tools.git
80 http://www.kernel.org/git/?p=utils/kernel/kexec/kexec-tools.git
110 1) Build a separate custom dump-capture kernel for capturing the
111 kernel core dump.
113 2) Or use the system kernel binary itself as dump-capture kernel and there is
114 no need to build a separate dump-capture kernel. This is possible
115 only with the architectures which support a relocatable kernel. As
117 relocatable kernel.
119 Building a relocatable kernel is advantageous from the point of view that
120 one does not have to build a second kernel for capturing the dump. But
121 at the same time one might want to build a custom dump capture kernel
127 System kernel config options
149 filesystems" menu if "Configure standard kernel features (for small
155 3) Enable "Compile the kernel with debug info" in "Kernel hacking."::
159 This causes the kernel to be built with debug symbols. The dump
163 Dump-capture kernel config options (Arch Independent)
166 1) Enable "kernel crash dumps" support under "Processor type and
177 Dump-capture kernel config options (Arch Dependent, i386 and x86_64)
189 2) With CONFIG_SMP=y, usually nr_cpus=1 need specified on the kernel
190 command line when loading the dump-capture kernel because one
191 CPU is enough for kdump kernel to dump vmcore on most of systems.
194 in kdump kernel. In this case, "disable_cpu_apicid=" is needed to
195 tell kdump kernel which cpu is 1st kernel's BSP. Please refer to
196 admin-guide/kernel-parameters.txt for more details.
200 3) A relocatable kernel is suggested to be built by default. If not yet,
201 enable "Build a relocatable kernel" support under "Processor type and
206 4) Use a suitable value for "Physical address where the kernel is
208 "kernel crash dumps" is enabled. A suitable value depends upon
209 whether kernel is relocatable or not.
211 If you are using a relocatable kernel use CONFIG_PHYSICAL_START=0x100000
212 This will compile the kernel for physical address 1MB, but given the fact
213 kernel is relocatable, it can be run from any physical address hence
215 kernel.
218 second kernel using boot parameter "crashkernel=Y@X". Here X is
219 start of memory region reserved for dump-capture kernel.
223 5) Make and install the kernel and its modules. DO NOT add this kernel
226 Dump-capture kernel config options (Arch Dependent, ppc64)
229 1) Enable "Build a kdump crash kernel" support under "Kernel" options::
233 2) Enable "Build a relocatable kernel" support::
237 Make and install the kernel and its modules.
239 Dump-capture kernel config options (Arch Dependent, ia64)
242 - No specific options are required to create a dump-capture kernel
244 above. This means that it is possible to use the system kernel
245 as a dump-capture kernel if desired.
248 kernel at runtime. This is done by specifying the base address as 0,
257 Dump-capture kernel config options (Arch Dependent, arm)
260 - To use a relocatable kernel,
265 Dump-capture kernel config options (Arch Dependent, arm64)
268 - Please note that kvm of the dump-capture kernel will not be enabled
276 Here 'size' specifies how much memory to reserve for the dump-capture kernel
278 "crashkernel=64M@16M" tells the system kernel to reserve 64 MB of memory
279 starting at physical address 0x01000000 (16MB) for the dump-capture kernel.
282 kernel at run time. This is done by specifying the base address as 0,
292 kernel will be aligned to a value (which is Arch dependent), so if the
301 the kernel command line to avoid a unbootable system after some memory has
327 When crashkernel=X,high is passed, kernel could allocate physical memory
343 2) Boot the system kernel with the boot parameter "crashkernel=Y@X".
346 start address 'X' is not necessary, kernel will search a suitable
353 dump-capture kernel config option notes above.
361 kernel will automatically locate the crash kernel image within the
365 the kernel, X if explicitly specified, must be aligned to 2MiB (0x200000).
370 After booting to the system kernel, dump-capture kernel needs to be
375 of dump-capture kernel. Following is the summary.
379 - Use bzImage/vmlinuz if kernel is relocatable.
380 - Use vmlinux if kernel is not relocatable.
403 to load dump-capture kernel::
405 kexec -p <dump-capture-kernel-vmlinux-image> \
406 --initrd=<initrd-for-dump-capture-kernel> --args-linux \
410 to load dump-capture kernel::
412 kexec -p <dump-capture-kernel-bzImage> \
413 --initrd=<initrd-for-dump-capture-kernel> \
417 to load dump-capture kernel::
419 kexec --type zImage -p <dump-capture-kernel-bzImage> \
420 --initrd=<initrd-for-dump-capture-kernel> \
421 --dtb=<dtb-for-dump-capture-kernel> \
425 to load dump-capture kernel::
427 kexec -p <dump-capture-kernel-Image> \
428 --initrd=<initrd-for-dump-capture-kernel> \
436 loading dump-capture kernel.
458 Notes on loading the dump-capture kernel:
470 due to shared interrupts in the dump-capture kernel.
475 * Boot parameter "1" boots the dump-capture kernel into single-user
478 * We generally don't have to bring up a SMP kernel just to capture the
480 kernel or specify maxcpus=1 option while loading dump-capture kernel.
484 * You should enable multi-cpu support in dump-capture kernel if you intend
488 SMP dump-capture kernel and specify maxcpus/nr_cpus, disable_cpu_apicid=[X]
492 the elfcorehdr= kernel parameter, it is used by the kdump kernel as it
493 is done on all other architectures. If no elfcorehdr= kernel parameter is
494 specified, the s390x kdump kernel dynamically creates the header. The
498 * For s390x systems with many attached devices the "cio_ignore" kernel
499 parameter should be used for the kdump kernel in order to prevent allocation
500 of kernel memory for devices that are not relevant for kdump. The same
508 After successfully loading the dump-capture kernel as previously
509 described, the system will reboot into the dump-capture kernel if a
516 will boot into the dump-capture kernel ( die_nmi() ).
520 the system will boot into the dump-capture kernel.
523 and the system will boot into the dump-capture kernel.
531 After the dump-capture kernel is booted, write out the dump file with
544 Before analyzing the dump image, you should reboot into a stable kernel.
557 ELF32-format headers using the --elf32-core-headers kernel option on the
558 dump kernel.
571 The kernel parameter, panic_on_warn, calls panic() in all WARN() paths. This
573 to specify this during runtime, /proc/sys/kernel/panic_on_warn can be set to 1
579 The kernel parameter panic_on_taint facilitates a conditional call to panic()