kdump

This is the short version of how kdump works: When the normal kernel (the 'boot' kernel) is booted, it reserves a part of system RAM it will normally never touch. This reservation is controlled by the crashkernel kernel commandline option.

当boot kernel 启动后，会预留一部分的内存，这些预留的内存被crashkernel 控制

During system startup an init script. loads another kernel (the 'kdump' kernel) into the reserved space. When a panic happens, control is transferred from the boot kernel to the kdump kernel. The kdump kernel boots up, using only the RAM reserved for it. It writes out a crash dump of the rest of RAM (the boot kernel's address space). Then it preforms a reboot, which will reset the machine and bring the boot kernel back up.

dump kernel 启动后，写出crash dump,然后重启，重新设置机器，然后带领boot kernel重新启动。

The main kernel that will be booted and run (until a crash happens, or new kernel is explicitly booted through kexec) is called the boot kernel. The only thing special about the boot kernel is that it needs a commandline option to prepare it for kdump/kexec use.

The kernel that gets booted when a crash happens, which performs the crash dump, is called the kdump kernel. This kernel needs to be built with support for being a kdump kernel, but that does not preclude its being used as a normal boot kernel.

kernel会重新启动，当crash 发生时，这个会执行故障转存的kernel 被称为kdump kernel.