From mboxrd@z Thu Jan  1 00:00:00 1970
From: Kay Sievers <kay.sievers@vrfy.org>
Date: Thu, 15 Apr 2010 04:47:12 +0000
Subject: Re: hotplug virtual disk to a Linux guest virtual machine with udev
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To: linux-hotplug@vger.kernel.org

On Wed, Apr 14, 2010 at 23:55, Shi Jin <jinzishuai@gmail.com> wrote:
> Thank Kay. Yes, I did check dmesg. In fact, this is how I know it when
> hot plug works.
> On ubuntu 9.10 and centos 5.4, the dmesg shows nothing while in FC12,
> it shows messages like
> [265565.693825] pci 0000:00:06.0: reg 10 io port: [0x00-0x3f]
> [265565.694573] pci 0000:00:02.0: BAR 6: bogus alignment [0x0-0x0] flags =
0x2
> [265565.694640] decode_hpp: Could not get hotplug parameters. Use defaults
> [265565.701747] virtio-pci 0000:00:06.0: enabling device (0000 -> 0001)
> [265565.702059] ACPI: PCI Interrupt Link [LNKB] enabled at IRQ 11
> [265565.702077] virtio-pci 0000:00:06.0: PCI INT A -> Link[LNKB] ->
> GSI 11 (level, high) -> IRQ 11
> [265565.702634] =C2=A0vdb: vdb1 vdb2

You can run:
  udevadm monitor
add a volume to the host and check if you get events for new block
devices. If you do, it's an issue with userspace in the system.

Kay