On Mon, Dec 22, 2008 at 10:08:42AM +1100, Michael Ellerman wrote: > On Tue, 2008-12-16 at 19:23 +0300, Anton Vorontsov wrote: > > This patch removes need for each platform to specify default kexec and > > crash kernel ops, thus effectively adds a working kexec support for most > > boards. > > > > Platforms that can't cope with default ops will explode in some weird > > way (a hang or reboot is most likely), which means that the board's > > kexec support should be fixed or blacklisted via dummy _prepare callback > > returning -ENOSYS. > > But where is the patch to do this?
The -ENOSYS dummy callback is a last resort thing to do when nobody cares or it's impossible to fix the Kexec on some board. We don't have any such boards (yet). > The chance of kexec working on some random machine that's never been > tested is pretty slim, every driver needs to be aware its hardware might > be in a weird state, The boards setup isn't always static. The Kexec might work perfectly well on a standalone board, but might hang with some weird PCI device attached to it (think that it might need some PCI fixup on shutdown). I think that a "Kexec tested to work on a particular board" term just doesn't exist. It might work, but it might hang with other setup on the *same* board. But in practice the Kexec work on every 6xx board I have. And I have pretty much of Freescale boards (almost all from the 83xx series), and I don't think it's practical to add #ifdef CONFIG_KEXEC into the every board file... Thus I don't think that disabling Kexec by default is a good idea. Plus, note that PowerPC port is the only one that disables Kexec by default (all other arches permit Kexec by default). > so enabling it by default is not a good idea IMHO. Why? A hang or plain/watchdog reboot is OK since kexec is as dangerous as trying to boot another kernel using "reboot -> u-boot -> new kernel" sequence -- it might not work, the new kernel might not boot for some reason. -- Anton Vorontsov email: cbouatmai...@gmail.com irc://irc.freenode.net/bd2 _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
