Directions for Kexec, Fastboot et. al

Suparna Bhattacharya

This BOF would be handled by:

Eric W. Biederman, ebiederm@xmission.com

Andy Pffifer , andyp@osdl.org

Suparna Bhattacharya, suparna@in.ibm.com

Kexec allows you to load and boot another kernel from the currently executing Linux kernel. This is useful for various things like very fast reboots, flexible bootloaders, crash dumping etc. Kexec has been around for a while now and has evolved based on feedback from the community.

The purpose of this BOF is to discuss how kexec would evolve and strategy for inclusion into the kernel main-stream.

Topics for discussion include:

1) Latest status and feedback so far from those who have tried it. How well it addresses various needs, problems faced, what could improve.

2) Kexec future:

(a) How do we get more exposure and greater testing for kexec ?

(b) What strategy should we use to achieve kexec's adoption into the mainline kernel?

- Do we need to maintain a database of successes and failures indexed by chipset & bios?

- Do we need more people using it?

- Should we be creating: whitepapers and user-guides; a sourceforge project; a set of utilities?

3) Experiences with architecture ports of kexec (e.g ppc64)and how it affects the generic parts of the code.

4) What is needed to make kexec more reliable?

(a) Issues related to quiescing devices and state of device shutdown

(b) Alternative ideas such as that of reserving a memory area for the kexec'ed kernel to boot into.

(c) Desirable characteristics for the kexec'ed (recovery) kernel (related question: can we avoid some of the h/w fixes ?)

5) Discuss the various reasons and potential uses for kexec and directions for any follow-on work that is required to address each of these categories

(a) Fast reboot:

Think about the possibility of avoiding device probing altogether, i.e. "here's what sysfs looked like before,please recreate it as fast as possible"

(b) Kexec on panic (and crash dump) issues

Some of the above could be resolved during the ensuing months, however other items are sure to be added to the list.