Re: [Lhms-devel] Re: [PATCH] register hot-added memory to iomemresource

[KAMEZAWA Hiroyuki]

On Thu, 27 Apr 2006 16:01:30 -0700
Andrew Morton <akpm@xxxxxxxx> wrote:

> KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote:
> >
> > This patch registers hot-added memory to iomem_resource.
> > By this, /proc/iomem can show hot-added memory.
> > This patch is against 2.6.17-rc2-mm1.
> > 
> > Note: kdump uses /proc/iomem to catch memory range when it is installed.
> >       So, kdump should be re-installed after /proc/iomem change.
> > 
> 
> What do you mean by "kdump should be reinstalled"?  The kdump userspace
> tools need to re-run kexec_load()?
> 
yes. I heard an admin has to re-run kexec_load.
- http://www.uwsg.indiana.edu/hypermail/linux/kernel/0604.0/0821.html
- http://www.uwsg.indiana.edu/hypermail/linux/kernel/0604.0/0829.html
Added CC to ebiederm@xxxxxxxxxxxx, nanhai.zou@xxxxxxxxx

> If so, why?
> 
It reads physical memory list from /proc/iomem now.
The physical memory list is read and saved at kdump kernel loading time
instead of crashing time. 

> And how is kdump to know that memory was hot-added?  Do we generate a
> hotplug event?
> 
A user program has to make memory section online from sysfs , anyway.

The hotplug script for memory hotplug will run at memory hotplug event 
from ACPI. If a user uses /probe interface (powerpc, x86_64),
he knows what he does. 

hot-add -> online memory -> kexec_load() is a scenario I think of.

Thanks,
-Kame



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