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Rebooting linux faster with kexec (and even faster with kexec-chooser!)

Somehow when reading through the Linux 2.6.17 changelog last week I came across a few articles discussing the kexec feature of recent Linux kernels. It's pretty neat, you can boot directly into another kernel image without having to go through a hardware / BIOS reboot. There's a Debian package called kexec-tools which gives you the ability to load these kernel images into memory and to boot into them. I found kexec a bit cumbersome to use, especially since all the kernels I care about booting into are the stock Debian kernels, and they all ship with ramdisk images that need to be used properly to boot. Using kexec by itself also requires that you have to manually bring the machine into a rebootable state first, or hack up some system scripts. You shouldn't just boot into a new kernel directly without shutting down devices, unmounting file systems, etc.

So to scratch this itch, I wrote kexec-chooser. It's a small Python script that will allow you to easily warm-reboot into any of the stock Debian kernels installed on your system. It'll probably work with custom kernels as well, but I haven't tested that yet :)

Downloads and more information can be found on the kexec-chooser page.

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