Gentoo Archives: gentoo-releng

From: Denys Fedoryshchenko <denys@××××××××.lb>
To: gentoo-releng@l.g.o
Subject: Re: [gentoo-releng] kexec compiled into kernel
Date: Mon, 28 Jan 2008 16:26:45
In Reply to: Re: [gentoo-releng] kexec compiled into kernel by Andrew Gaffney
For example you compile new kernel, and you want to test it without 
installing in boot loader. It is very useful, especially when it is remote 
machine with grub, grub "one time load" not so useful like lilo -R, plus each 
operation with boot loader causing risk to make system inoperable, even by 

1)compile tools
emerge kexec-tools
2)Load kernel to memory (kexec have to be compiled in kernel)
kexec -l /path/kernelname --append="root=/dev/rootdevice panic=5"
3)When you are ready (sync, also highly recommended to unmount partitions or 
remount read-only), LAUNCH! :-)
kexec -e

system will start booting new kernel, without complete hardware reset. There 
is some issues with buggy drivers, like intel wireless 3945, i wrote 
bugreport to intel, and probably will be fixed soon. But hardware cases with 
kexec very rare, and it works just great for me.

They only one thing stopping me to contribute few scripts and tips - my 
crappy english.

On Mon, 28 Jan 2008 10:17:58 -0600, Andrew Gaffney wrote
> Denys Fedoryshchenko wrote: > > Hi > > > > Is it possible to compile in kernel kexec support? at least for
> > where it is well supported. > > > > It is very handy, when Gentoo installed on PC remotely on regular PC,
> > people there just boot CD and set ip, and leave location for few days. > > It is not possible to eject CD on remote PC, cause on reboot BIOS usually > > closing tray. kexec will let to reboot system to newly compiled kernel > > without full reboot, avoiding system to boot from CD again. Remote tech's
> > location can remove CD later, when it is comfortable for them. > > How is kexec used? Are there commandline utilities for it? Is it > triggered through a /proc interface? > > -- > Andrew Gaffney
> Gentoo Linux Developer Catalyst/Installer + x86 release
> -- > gentoo-releng@l.g.o mailing list
-- Denys Fedoryshchenko Technical Manager Virtual ISP S.A.L. -- gentoo-releng@l.g.o mailing list