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
76 http://www.kernel.org/pub/scm/utils/kernel/kexec/kexec-tools.git
79 http://www.kernel.org/git/?p=utils/kernel/kexec/kexec-tools.git
109 1) Build a separate custom dump-capture kernel for capturing the
110 kernel core dump.
112 2) Or use the system kernel binary itself as dump-capture kernel and there is
113 no need to build a separate dump-capture kernel. This is possible
114 only with the architectures which support a relocatable kernel. As
116 kernel.
118 Building a relocatable kernel is advantageous from the point of view that
119 one does not have to build a second kernel for capturing the dump. But
120 at the same time one might want to build a custom dump capture kernel
126 System kernel config options
139 filesystems" menu if "Configure standard kernel features (for small
145 3) Enable "Compile the kernel with debug info" in "Kernel hacking."
149 This causes the kernel to be built with debug symbols. The dump
153 Dump-capture kernel config options (Arch Independent)
156 1) Enable "kernel crash dumps" support under "Processor type and
166 Dump-capture kernel config options (Arch Dependent, i386 and x86_64)
181 (If CONFIG_SMP=y, then specify maxcpus=1 on the kernel command line
182 when loading the dump-capture kernel, see section "Load the Dump-capture
185 3) If one wants to build and use a relocatable kernel,
186 Enable "Build a relocatable kernel" support under "Processor type and
191 4) Use a suitable value for "Physical address where the kernel is
193 "kernel crash dumps" is enabled. A suitable value depends upon
194 whether kernel is relocatable or not.
196 If you are using a relocatable kernel use CONFIG_PHYSICAL_START=0x100000
197 This will compile the kernel for physical address 1MB, but given the fact
198 kernel is relocatable, it can be run from any physical address hence
200 kernel.
203 second kernel using boot parameter "crashkernel=Y@X". Here X is
204 start of memory region reserved for dump-capture kernel.
208 5) Make and install the kernel and its modules. DO NOT add this kernel
211 Dump-capture kernel config options (Arch Dependent, ppc64)
214 1) Enable "Build a kdump crash kernel" support under "Kernel" options:
218 2) Enable "Build a relocatable kernel" support
222 Make and install the kernel and its modules.
224 Dump-capture kernel config options (Arch Dependent, ia64)
227 - No specific options are required to create a dump-capture kernel
229 above. This means that it is possible to use the system kernel
230 as a dump-capture kernel if desired.
233 kernel at run time. This is done by specifying the base address as 0,
241 kernel will be aligned to 64Mb, so if the start address is not then
244 Dump-capture kernel config options (Arch Dependent, arm)
247 - To use a relocatable kernel,
258 the kernel command line to avoid a unbootable system after some memory has
291 2) Boot the system kernel with the boot parameter "crashkernel=Y@X",
292 where Y specifies how much memory to reserve for the dump-capture kernel
294 "crashkernel=64M@16M" tells the system kernel to reserve 64 MB of memory
295 starting at physical address 0x01000000 (16MB) for the dump-capture kernel.
303 dump-capture kernel config option notes above.
310 On arm, use "crashkernel=Y@X". Note that the start address of the kernel
312 any space below the alignment point may be overwritten by the dump-capture kernel,
319 After booting to the system kernel, dump-capture kernel needs to be
324 of dump-capture kernel. Following is the summary.
327 - Use vmlinux if kernel is not relocatable.
328 - Use bzImage/vmlinuz if kernel is relocatable.
339 to load dump-capture kernel.
341 kexec -p <dump-capture-kernel-vmlinux-image> \
342 --initrd=<initrd-for-dump-capture-kernel> --args-linux \
346 to load dump-capture kernel.
348 kexec -p <dump-capture-kernel-bzImage> \
349 --initrd=<initrd-for-dump-capture-kernel> \
353 to load dump-capture kernel.
355 kexec --type zImage -p <dump-capture-kernel-bzImage> \
356 --initrd=<initrd-for-dump-capture-kernel> \
357 --dtb=<dtb-for-dump-capture-kernel> \
366 loading dump-capture kernel.
380 Notes on loading the dump-capture kernel:
392 due to shared interrupts in the dump-capture kernel.
397 * Boot parameter "1" boots the dump-capture kernel into single-user
400 * We generally don' have to bring up a SMP kernel just to capture the
402 kernel or specify maxcpus=1 option while loading dump-capture kernel.
405 the elfcorehdr= kernel parameter, it is used by the kdump kernel as it
406 is done on all other architectures. If no elfcorehdr= kernel parameter is
407 specified, the s390x kdump kernel dynamically creates the header. The
411 * For s390x systems with many attached devices the "cio_ignore" kernel
412 parameter should be used for the kdump kernel in order to prevent allocation
413 of kernel memory for devices that are not relevant for kdump. The same
421 After successfully loading the dump-capture kernel as previously
422 described, the system will reboot into the dump-capture kernel if a
429 will boot into the dump-capture kernel ( die_nmi() ).
433 the system will boot into the dump-capture kernel.
436 and the system will boot into the dump-capture kernel.
444 After the dump-capture kernel is booted, write out the dump file with
453 Before analyzing the dump image, you should reboot into a stable kernel.
466 ELF32-format headers using the --elf32-core-headers kernel option on the
467 dump kernel.
477 The kernel parameter, panic_on_warn, calls panic() in all WARN() paths. This
479 to specify this during runtime, /proc/sys/kernel/panic_on_warn can be set to 1