On Tue, 2012-07-10 at 16:56 -0600, Khalid Aziz wrote: > On Fri, 2012-07-06 at 15:00 -0600, Toshi Kani wrote: > > Yes, offlining and eject are similar operations to a core as it alone > > cannot be removed physically. Ejecting a core is a logical eject > > operation, which updates the status (_STA) of the object in ACPI after > > offlining. The difference from the offlining is that the ejected core > > is no longer assigned to the partition. Here is one example. Say, a > > core is assigned to a guest partition as a dedicated resource (ex. 100% > > of its CPU time is bound to the partition). Offlining this core saves > > the power-consumption, but this core is still bound to the partition. > > Ejecting the core removes it from the partition (logically), and allows > > it to be assigned to other partition as a dedicated resource with > > hot-add. > > > > Ejecting a core is reasonable when eject happens from a guest. I still > wonder what firmware would do if kernel calls eject method on a core > when running on the native host platform. If firmware behavior is not > well defined in this case, there might be some risk associated with > calling eject method on core. > > Makes sense? No, that's not the case. The firmware only implements _EJ0 when it supports the behavior on the environment. It is true for both native and virtual platforms. Note that the presence of a CPU is abstracted with _STA in ACPI, so it does not matter to the kernel if an eject is a physical or logical operation. For example, HP Superdome 2 implements _EJ0 on the native platform to support capacity-on-demand and RAS features (which are supported by HP-UX). _EJ0 is still a logical eject operation in this case. Thanks, -Toshi -- 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
