Re: [Qemu-devel] [PATCH RFC v2 0/7] coordinate cpu hotplug/unplug bewteen QEMU and kernel by EC

["Michael S. Tsirkin" <mst@redhat.com>]

On Thu, Jun 06, 2013 at 11:16:53AM +0800, liguang wrote:
> v2: 
> 1.remove PIIX4_PROC_BASE operations for cpu hotplug
> 2.fix wrong description fo cpu-del
> 
> patch 1 adds ACPI Embedded Controller (EC),
> refer-to:
> ACPI SPEC v5 chapter 12
> "ACPI Embedded Controller Interface Specification"
> 
> EC is a standard ACPI device, it plays flexible roles,
> especially be event carrier, it can pass events between platform
> and OS, so OS can execute _Qxx method which defined
> by yourself and query EC's ACPI space which can be a buffer for
> many purposes
> 
> here, I want to deliver CPU online/offline event between
> OS and QEMU for CPU hotplug feature, then we will don't
> need to "echo 1 > /sys/devices/system/cpu/cpu1/online"
> again after 'cpu-add' and also for offline to do real cpu
> removal.

So, it's another channel to the guest.
Can't qemu-ga do this in userspace, using the existing channel?

> what I am trying to do is emulated physical addition/removal
> (like described by linux kernel document for cpu hotplug --
> linux-2.6/Documentation/cpu-hotplug.txt) for QEMU.
> 
> these RFC patches are sent for demo what I am trying to do.
> 
> the design process simply like following:
> 
> hotplug
> qemu::ec::sci -> kernel::ec::gpe::notifier->
> kernel::cpu_physic_hotplug::handler->kernel::cpu_up
> 
> unplug
> kernel::cpu_down::kernel::cpu_physic_hotplug::handler->
> kernel::ec::ec_write->qemu::ec::->qemu::cpu-unplug
> 
> sorry, I should poll cpu-unplug cmd sent from kernel,
> but, it's a little trivial, I want do it later.
> 
> for kernel patches:
> http://comments.gmane.org/gmane.linux.kernel/1503460
> 
> 
> Li Guang (8)
> 	 acpi: add ACPI Embedded Controller support
> 	 ich9: add notifer for ec to generate sci
> 	 ec: add operations for _Qxx events
> 	 piix4: add notifer for ec to generate sci
> 	 piix4: add events for cpu hotplug
> 	 qmp: add 'cpu-del' command
> 	 pc: add EC qdev init for piix & q35
> 	 cpu-hotplug: remove memory regison for cpu hotplug
> 
> default-configs/x86_64-softmmu.mak |   1 +
> hw/acpi/Makefile.objs              |   1 +
> hw/acpi/ec.c                       | 225 ++++++++++++++++++++++++++++++++++++
> hw/acpi/ich9.c                     |  15 +++++++++++++++
> hw/acpi/piix4.c                    |  68 ++++++++++++++
> hw/i386/pc.c                       |  46 ++++++++++++++++++++++++++++--
> hw/i386/pc_piix.c                  |   7 +
> hw/i386/pc_q35.c                   |   6 +
> include/hw/acpi/ec.h               |  44 ++++++
> include/hw/acpi/ich9.h             |   1 +
> include/hw/boards.h                |   5 +++--
> include/hw/i386/pc.h               |   1 +
> qapi-schema.json                   |  13 +++++++++++++
> qmp-commands.hx                    |  23 +++++++++++++++++++++++
> qmp.c                              |   9 +++++++++
> 15 files changed, 411 insertions(+), 54 deletions(-)
>  create mode 100644 hw/acpi/ec.c
>  create mode 100644 include/hw/acpi/ec.h