Re: A udev rule to serve the change event of ACPI container?
From: Michal Hocko
Date: Tue Jul 11 2017 - 04:26:19 EST
On Mon 26-06-17 10:59:07, Michal Hocko wrote:
> On Mon 26-06-17 14:26:57, Joey Lee wrote:
> > Hi all,
> > If ACPI received ejection request for a ACPI container, kernel
> > emits KOBJ_CHANGE uevent when it found online children devices
> > below the acpi container.
> > Base on the description of caa73ea15 kernel patch, user space
> > is expected to offline all devices below the container and the
> > container itself. Then, user space can finalize the removal of
> > the container with the help of its ACPI device object's eject
> > attribute in sysfs.
> > That means that kernel relies on users space to peform the offline
> > and ejection jobs to acpi container and children devices. The
> > discussion is here:
> > https://lkml.org/lkml/2013/11/28/520
> > The mail loop didn't explain why the userspace is responsible for
> > the whole container offlining. Is it possible to do that transparently
> > from the kernel? What's the difference between offlining memory and
> > processors which happends without any cleanup and container which
> > does essentially the same except it happens at once?
> > - After a couple of years, can we let the container hot-remove
> > process transparently?
> > - Except udev rule, does there have any other mechanism to trigger
> > auto offline/ejection?
> I would be also interested whether the kernel can simply send an udev event
> to all devices in the container.
Any opinion on this?