regardless of where the kernel loads. Therefore, kexec backs up this
region just before rebooting into the dump-capture kernel.
+Similarly on PPC64 machines first 32KB of physical memory is needed for
+booting regardless of where the kernel is loaded and to support 64K page
+size kexec backs up the first 64KB memory.
+
All of the necessary information about the system kernel's core image is
encoded in the ELF format, and stored in a reserved area of memory
before a crash. The physical address of the start of the ELF header is
Dump-capture kernel config options (Arch Dependent, ppc64)
----------------------------------------------------------
-- Make and install the kernel and its modules. DO NOT add this kernel
+* Make and install the kernel and its modules. DO NOT add this kernel
to the boot loader configuration files.
Dump-capture kernel config options (Arch Dependent, ia64)
Boot into System Kernel
=======================
-1) Make and install the kernel and its modules. Update the boot loader
- (such as grub, yaboot, or lilo) configuration files as necessary.
+1) Update the boot loader (such as grub, yaboot, or lilo) configuration
+ files as necessary.
2) Boot the system kernel with the boot parameter "crashkernel=Y@X",
where Y specifies how much memory to reserve for the dump-capture kernel
loading dump-capture kernel.
For i386, x86_64 and ia64:
- "init 1 irqpoll maxcpus=1"
+ "1 irqpoll maxcpus=1"
For ppc64:
- "init 1 maxcpus=1 noirqdistrib"
+ "1 maxcpus=1 noirqdistrib"
Notes on loading the dump-capture kernel:
* You must specify <root-dev> in the format corresponding to the root
device name in the output of mount command.
-* "init 1" boots the dump-capture kernel into single-user mode without
- networking. If you want networking, use "init 3."
+* Boot parameter "1" boots the dump-capture kernel into single-user
+ mode without networking. If you want networking, use "3".
* We generally don' have to bring up a SMP kernel just to capture the
dump. Hence generally it is useful either to build a UP dump-capture
is called inside interrupt context or die() is called and panic_on_oops is set,
the system will boot into the dump-capture kernel.
-On powererpc systems when a soft-reset is generated, die() is called by all cpus and the system will boot into the dump-capture kernel.
+On powererpc systems when a soft-reset is generated, die() is called by all cpus
+and the system will boot into the dump-capture kernel.
For testing purposes, you can trigger a crash by using "ALT-SysRq-c",
-"echo c > /proc/sysrq-trigger or write a module to force the panic.
+"echo c > /proc/sysrq-trigger" or write a module to force the panic.
Write Out the Dump File
=======================
To Do
=====
-1) Provide a kernel pages filtering mechanism, so core file size is not
- extreme on systems with huge memory banks.
-
-2) Relocatable kernel can help in maintaining multiple kernels for
- crash_dump, and the same kernel as the system kernel can be used to
- capture the dump.
+1) Provide relocatable kernels for all architectures to help in maintaining
+ multiple kernels for crash_dump, and the same kernel as the system kernel
+ can be used to capture the dump.
Contact