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Date: Fri, 12 Nov 2010 11:18:57 +0200
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Subject: [Qemu-devel] Re: Cannot not unplug cold-plugged devices
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To: Isaku Yamahata <yamahata@valinux.co.jp>
Cc: Cam Macdonell <cam@cs.ualberta.ca>, "qemu-devel@nongnu.org Developers" <qemu-devel@nongnu.org>

On Fri, Nov 12, 2010 at 04:24:11PM +0900, Isaku Yamahata wrote:
> On Thu, Nov 11, 2010 at 11:29:39PM -0700, Cam Macdonell wrote:
> > Hi,
> > 
> > I was trying to do a "device_del" on my ivshmem device and it won't
> > work unless the device is added via hotplug.  If the device is
> > coldplugged (added at startup) then nothing happens.  I think I
> > tracked this behaviour to the patch below.
> > 
> > Is not allowing coldplugged devices to be unplugged the desired behaviour?
> 
> Oh, my bad. Does the following patch help?
> 
> >From 45914b2fc95750b65685dfb98a435f58e38b45ba Mon Sep 17 00:00:00 2001
> Message-Id: <45914b2fc95750b65685dfb98a435f58e38b45ba.1289546596.git.yamahata@valinux.co.jp>
> From: Isaku Yamahata <yamahata@valinux.co.jp>
> Date: Fri, 12 Nov 2010 16:21:35 +0900
> Subject: [PATCH] acpi/piix4: allow pci hotplug for cold plugged device.
> 
> This patch fixes 5beb8ad503c88a76f2b8106c3b74b4ce485a60e1
> reported by Cam Macdonell <cam@cs.ualberta.ca>.
> Before the change set, cold plugged device can be hot unplugged.
> This patch unbreaks it.
> 
> Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>



> ---
>  hw/acpi_piix4.c |    4 +++-
>  1 files changed, 3 insertions(+), 1 deletions(-)
> 
> diff --git a/hw/acpi_piix4.c b/hw/acpi_piix4.c
> index 66c7885..bca330e 100644
> --- a/hw/acpi_piix4.c
> +++ b/hw/acpi_piix4.c
> @@ -621,8 +621,10 @@ static int piix4_device_hotplug(DeviceState *qdev, PCIDevice *dev, int state)
>      PIIX4PMState *s = DO_UPCAST(PIIX4PMState, dev,
>                                  DO_UPCAST(PCIDevice, qdev, qdev));
>  
> -    if (!dev->qdev.hotplugged)
> +    /* qemu initialization case */

That comment is pretty obscure :)


> +    if (state && !dev->qdev.hotplugged) {
>          return 0;
> +    }

Do we even need this check at all?

>  
>      s->pci0_status.up = 0;
>      s->pci0_status.down = 0;
> -- 
> 1.7.1.1
> 
> 
> 
> -- 
> yamahata