• From: forest town, lake land
  • Registered: 2011-02-26
  • Posts: 358

Topic: Faster reboots with kexec

kexec changes your reboot to skip BIOS + GRUB. If you are rebooting often, or like me have a damaged CMOS battery connector, it can be handy to have installed. Fortunately for us crunchbangers it is amazingly easy to install on debian.

Stolen from here.

Step 1

sudo apt-get install kexec-tools

Step 2

sudo dpkg-reconfigure kexec-tools

Answer yes in the dialog box.

Step 3

Shutdown (NOT REBOOT!!) and restart your PC and marvel at how fast reboots are (or in my case that you don't have to reset your clock smile )

Potential caveats

Some hardware may not appreciate kexec, as not all hardware will get fully reinitialized.

If you are dual booting, this will be less useful, as a reboot will skip BIOS and GRUB phases of boot.

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  • jvd
  • #! CrunchBanger
  • Offline
  • Registered: 2010-01-29
  • Posts: 193

Re: Faster reboots with kexec

Sounds very cool! Found coreboot yesterday, but my hardware is not supported.

How to revert to the normal booting if there would be some error? It seems quite likely that one would have to get a screwdriver when this goes wrong hmm

  • From: forest town, lake land
  • Registered: 2011-02-26
  • Posts: 358

Re: Faster reboots with kexec

How to revert to the normal booting if there would be some error? It seems quite likely that one would have to get a screwdriver when this goes wrong.

Shouldn't be a problem. This only affects reboots. A fresh boot will still work, then you would just have to do the dpkg-reconfigure again, selecting no when prompted, and uninstall kexec-tools to be back to regular reboots.

Apt Pinning - Pulseaudio - Nvidia Drivers - Laptop Power Saving - 3G Bandwidth Logging -  obmocmenu
  • iann
  • #! CrunchBanger
  • Offline
  • Registered: 2010-09-10
  • Posts: 223

Re: Faster reboots with kexec

kexec essentially just launches a kernel directly from another kernel.  It isn't strictly a reboot and many reboot steps are skipped.

  • From: forest town, lake land
  • Registered: 2011-02-26
  • Posts: 358

Re: Faster reboots with kexec

iann wrote:

kexec essentially just launches a kernel directly from another kernel.  It isn't strictly a reboot and many reboot steps are skipped.

You are correct. This is not for everyone. Due to the skipped reboot steps it is very hardware dependant. I am doing it mostly because of my broken CMOS battery. This way I only have to set my time when I power off my machine. Snappy "reboots" are a side effect.

Apt Pinning - Pulseaudio - Nvidia Drivers - Laptop Power Saving - 3G Bandwidth Logging -  obmocmenu
  • Awebb
  • #! Die-hard
  • Offline
  • Registered: 2009-07-23
  • Posts: 2,471

Re: Faster reboots with kexec

This method is meant to spare us the reboot after a kernel update. We are still far away from switching the kernel ad-hoc.

I'm so meta, even this acronym