Hi Michal, Sorry for my delay. On Tue, Jul 11, 2017 at 10:25:32AM +0200, Michal Hocko wrote: > 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? If BIOS emits ejection event for a ACPI0004 container, someone needs to handle the offline/eject jobs of container. Either kernel or user space. Only sending uevent to individual child device can simplify udev rule, but it also means that the kernel needs to offline/eject container after all children devices are offlined. Maybe adding a ejection flag on the ACPI0004 object to indicate the container state. But, if userland doesn't do his job, then the timing to reset the flag will be the problem. Thanks a lot! Joey Lee -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
