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. Therefore, kexec backs up this
31 region just before rebooting into the dump-capture kernel.
34 booting regardless of where the kernel is loaded and to support 64K page
38 with the region [0, crashkernel region size] and then the kdump kernel
39 runs in [0, crashkernel region size]. Therefore no relocatable kernel is
42 All of the necessary information about the system kernel's core image is
45 passed to the dump-capture kernel through the elfcorehdr= boot
50 With the dump-capture kernel, you can access the memory image through
68 http://kernel.org/pub/linux/utils/kernel/kexec/kexec-tools.tar.gz
74 - git://git.kernel.org/pub/scm/utils/kernel/kexec/kexec-tools.git
75 - http://www.kernel.org/pub/scm/utils/kernel/kexec/kexec-tools.git
78 http://www.kernel.org/git/?p=utils/kernel/kexec/kexec-tools.git
108 1) Build a separate custom dump-capture kernel for capturing the
109 kernel core dump.
111 2) Or use the system kernel binary itself as dump-capture kernel and there is
112 no need to build a separate dump-capture kernel. This is possible
113 only with the architectures which support a relocatable kernel. As
115 relocatable kernel.
117 Building a relocatable kernel is advantageous from the point of view that
118 one does not have to build a second kernel for capturing the dump. But
119 at the same time one might want to build a custom dump capture kernel
125 System kernel config options
138 filesystems" menu if "Configure standard kernel features (for small
144 3) Enable "Compile the kernel with debug info" in "Kernel hacking."::
148 This causes the kernel to be built with debug symbols. The dump
152 Dump-capture kernel config options (Arch Independent)
155 1) Enable "kernel crash dumps" support under "Processor type and
166 Dump-capture kernel config options (Arch Dependent, i386 and x86_64)
183 (If CONFIG_SMP=y, then specify maxcpus=1 on the kernel command line
184 when loading the dump-capture kernel, see section "Load the Dump-capture
187 3) If one wants to build and use a relocatable kernel,
188 Enable "Build a relocatable kernel" support under "Processor type and
193 4) Use a suitable value for "Physical address where the kernel is
195 "kernel crash dumps" is enabled. A suitable value depends upon
196 whether kernel is relocatable or not.
198 If you are using a relocatable kernel use CONFIG_PHYSICAL_START=0x100000
199 This will compile the kernel for physical address 1MB, but given the fact
200 kernel is relocatable, it can be run from any physical address hence
202 kernel.
205 second kernel using boot parameter "crashkernel=Y@X". Here X is
206 start of memory region reserved for dump-capture kernel.
210 5) Make and install the kernel and its modules. DO NOT add this kernel
213 Dump-capture kernel config options (Arch Dependent, ppc64)
216 1) Enable "Build a kdump crash kernel" support under "Kernel" options::
220 2) Enable "Build a relocatable kernel" support::
224 Make and install the kernel and its modules.
226 Dump-capture kernel config options (Arch Dependent, ia64)
229 - No specific options are required to create a dump-capture kernel
231 above. This means that it is possible to use the system kernel
232 as a dump-capture kernel if desired.
235 kernel at run time. This is done by specifying the base address as 0,
245 kernel will be aligned to 64Mb, so if the start address is not then
248 Dump-capture kernel config options (Arch Dependent, arm)
251 - To use a relocatable kernel,
256 Dump-capture kernel config options (Arch Dependent, arm64)
259 - Please note that kvm of the dump-capture kernel will not be enabled
269 the kernel command line to avoid a unbootable system after some memory has
296 2) Boot the system kernel with the boot parameter "crashkernel=Y@X",
297 where Y specifies how much memory to reserve for the dump-capture kernel
299 "crashkernel=64M@16M" tells the system kernel to reserve 64 MB of memory
300 starting at physical address 0x01000000 (16MB) for the dump-capture kernel.
308 dump-capture kernel config option notes above.
316 kernel will automatically locate the crash kernel image within the
320 the kernel, X if explicitly specified, must be aligned to 2MiB (0x200000).
325 After booting to the system kernel, dump-capture kernel needs to be
330 of dump-capture kernel. Following is the summary.
334 - Use vmlinux if kernel is not relocatable.
335 - Use bzImage/vmlinuz if kernel is relocatable.
358 to load dump-capture kernel::
360 kexec -p <dump-capture-kernel-vmlinux-image> \
361 --initrd=<initrd-for-dump-capture-kernel> --args-linux \
365 to load dump-capture kernel::
367 kexec -p <dump-capture-kernel-bzImage> \
368 --initrd=<initrd-for-dump-capture-kernel> \
372 to load dump-capture kernel::
374 kexec --type zImage -p <dump-capture-kernel-bzImage> \
375 --initrd=<initrd-for-dump-capture-kernel> \
376 --dtb=<dtb-for-dump-capture-kernel> \
380 to load dump-capture kernel::
382 kexec -p <dump-capture-kernel-Image> \
383 --initrd=<initrd-for-dump-capture-kernel> \
391 loading dump-capture kernel.
413 Notes on loading the dump-capture kernel:
425 due to shared interrupts in the dump-capture kernel.
430 * Boot parameter "1" boots the dump-capture kernel into single-user
433 * We generally don't have to bring up a SMP kernel just to capture the
435 kernel or specify maxcpus=1 option while loading dump-capture kernel.
439 * You should enable multi-cpu support in dump-capture kernel if you intend
443 SMP dump-capture kernel and specify maxcpus/nr_cpus, disable_cpu_apicid=[X]
447 the elfcorehdr= kernel parameter, it is used by the kdump kernel as it
448 is done on all other architectures. If no elfcorehdr= kernel parameter is
449 specified, the s390x kdump kernel dynamically creates the header. The
453 * For s390x systems with many attached devices the "cio_ignore" kernel
454 parameter should be used for the kdump kernel in order to prevent allocation
455 of kernel memory for devices that are not relevant for kdump. The same
463 After successfully loading the dump-capture kernel as previously
464 described, the system will reboot into the dump-capture kernel if a
471 will boot into the dump-capture kernel ( die_nmi() ).
475 the system will boot into the dump-capture kernel.
478 and the system will boot into the dump-capture kernel.
486 After the dump-capture kernel is booted, write out the dump file with
495 Before analyzing the dump image, you should reboot into a stable kernel.
508 ELF32-format headers using the --elf32-core-headers kernel option on the
509 dump kernel.
522 The kernel parameter, panic_on_warn, calls panic() in all WARN() paths. This
524 to specify this during runtime, /proc/sys/kernel/panic_on_warn can be set to 1
530 The kernel parameter panic_on_taint facilitates a conditional call to panic()