What are kexec tools?
kexec is a system call that enables you to load and boot into another kernel from the currently running kernel. kexec performs the function of the boot loader from within the kernel.
How kexec works?
Essentially, kexec skips the bootloader stage and hardware initialization phase performed by the system firmware (BIOS or UEFI), and directly loads the new kernel into main memory and starts executing it immediately.
What is initrd used for?
In computing (specifically as regards Linux computing), initrd (initial ramdisk) is a scheme for loading a temporary root file system into memory, which may be used as part of the Linux startup process.
How do I reboot with kexec?
After running kexec-reboot, simply reboot your system normally….Usage
- -i , –interactive. Choose the kernel to stage from a list.
- -l , –latest. Stage the latest kernel.
- -r , –reboot. Reboot immediately after staging the kernel.
- -v , –[no-]verbose. Extra verbosity.
What is Vmcore?
From Wikipedia, the free encyclopedia. kdump is a feature of the Linux kernel that creates crash dumps in the event of a kernel crash. When triggered, kdump exports a memory image (also known as vmcore) that can be analyzed for the purposes of debugging and determining the cause of a crash.
How do I disable kexec?
This behaviour can be modified by setting the flag LOAD_EXEC in the file /etc/default/kexec to false. Note: After changing the flag, shutdown and boot the system for the change to take effect.
How do I disable Kexec?
Is initrd necessary?
5 Answers. initrd/initramfs is optional and not a requirement. bzImage is the pure kernel image and can be booted directly by the bootloader.
What is difference between initrd and initramfs?
Both initrd and ramfs are zipped at compile time, but the difference is, initrd is a block device unpacked to be mounted by the kernel at booting, while ramfs is unpacked via cpio into memory.
How do I read a Vmcore file?
To quickly view the contents of vmcore-dmesg. txt, open the file in a text editor or grep for the word crash with the cat vmcore-dmesg. txt | grep -i crash command. As you can see, SysRq triggered a crash when you issued the echo commands.
What is var crash?
/var/crash : System crash dumps (optional) This directory holds system crash dumps. As of the date of this release of the standard, system crash dumps were not supported under Linux but may be supported by other systems which may comply with the FHS.
What does kexec do in the Linux kernel?
kexec is a system call that enables you to load and boot into another kernel from the currently running kernel. kexec performs the function of the boot loader from within the kernel.
What is the optional initrd image for kexec?
The optional initrd-image is the initrd image to be used during boot. It’s also possible to invoke kexec without an option parameter. In that case, kexec loads the specified kernel and then invokes shutdown(1).
Is there way to invoke kexec without option parameter?
Passing the exact contents of /proc/cmdline into command-line-options is the safest way to ensure that correct values are passed to the rebooting kernel. The optional initrd-image is the initrd image to be used during boot. It’s also possible to invoke kexec without an option parameter.