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From: Bandan Das <bsd@redhat.com>
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Date: Thu, 14 Jul 2016 13:49:55 -0400
In-Reply-To: <1468515285-173356-5-git-send-email-imammedo@redhat.com> (Igor
	Mammedov's message of "Thu, 14 Jul 2016 18:54:33 +0200")
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Subject: Re: [Qemu-devel] [PATCH v4 04/16] pc: forbid BSP removal
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To: Igor Mammedov <imammedo@redhat.com>
Cc: qemu-devel@nongnu.org, pkrempa@redhat.com, ehabkost@redhat.com, mst@redhat.com, eduardo.otubo@profitbricks.com

Igor Mammedov <imammedo@redhat.com> writes:

> BSP is assumed to always present in QEMU code, so
> untile that assumptions are gone, deny removal request.
> In another words QEMU won't support BSP hot-unplug.
>
> Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> ---
>  hw/i386/pc.c | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index 5a67f15..33c5f97 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -1751,10 +1751,17 @@ out:
>  static void pc_cpu_unplug_request_cb(HotplugHandler *hotplug_dev,
>                                       DeviceState *dev, Error **errp)
>  {
> +    int idx;
>      HotplugHandlerClass *hhc;
>      Error *local_err = NULL;
>      PCMachineState *pcms = PC_MACHINE(hotplug_dev);
>  
> +    pc_find_cpu_slot(pcms, CPU(dev), &idx);
> +    if (idx == 0) {
> +        error_setg(&local_err, "1st CPU (BSP) is unpluggable");
> +        goto out;
> +    }

Nit: Boot CPU or simply Bootstrap Processor sounds better IMO.

>      hhc = HOTPLUG_HANDLER_GET_CLASS(pcms->acpi_dev);
>      hhc->unplug_request(HOTPLUG_HANDLER(pcms->acpi_dev), dev, &local_err);