(8/14/13 2:23 PM), Tejun Heo wrote:
Hello,
On Wed, Aug 14, 2013 at 02:15:44PM -0400, KOSAKI Motohiro wrote:
I don't follow this. We need to think why memory hotplug is necessary.
Because system reboot is unacceptable on several critical services. Then,
if someone set wrong boot option, systems SHOULD fail to boot. At that time,
admin have a chance to fix their mistake. In the other hand, after running
production service, they have no chance to fix the mistake. In general, default
boot option should have a fallback and non-default option should not have a
fallback. That's a fundamental rule.
The fundamental rule is that the system has to boot.
I don't agree it. Please look at other kernel options. A lot of these don't
follow you. These behave as direction, not advise.
I mean the fallback should be implemented at turning on default the feature.
Your argument is
pointless as the kernel has no control over where its own image is
placed w.r.t. hotpluggable nodes. So, are we gonna fail boot if
kernel image intersects hotpluggable node and the option is specified
even if memory hotplug can be used on other nodes? That doesn't make
any sense.
I don't read whole discussion and I don't quite understand why no kernel
place controlling is relevant. Every unpluggable node is suitable for
kernel. If you mean current kernel placement logic don't care plugging,
that's a bug.
If we aim to hot remove, we have to have either kernel relocation or
hotplug awre kernel placement at boot time.
Failing to boot is *way* worse reporting mechanism than almost
everything else. If the sysadmin is willing to risk machines failing
to come up, she would definitely be willing to check whether which
memory areas are actually hotpluggable too, right?
No. see above. Your opinion is not pragmatic useful.
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