Re: Why doesn't Intel e1000 NIC work correctly in Windows XP?

[Jan Kiszka <jan.kiszka@siemens.com>]

On 2011-06-15 10:04, Jan Kiszka wrote:
> On 2011-06-15 02:54, Alex Williamson wrote:
>> On Tue, 2011-06-14 at 16:11 +0800, Flypen CloudMe wrote:
>>> Hi,
>>>
>>> I use Redhat Enterprise Linux 6, and use the KVM that is released by
>>> Redhat officially. The kernel version is 2.6.32-71.el6.x86_64.
>>>
>>> It seems that the IRQs are conflicted after reboot. The NIC and the
>>> SCSI controller have the same IRQ number. If I re-install the NIC
>>> driver, the IRQ number of the NIC will be assigned another value, then
>>> it can work normally. Do we have a way to let the NIC and the SCSI
>>> controller have different IRQ number in VM?
>>
>> I'll see if I can reproduce and figure anything out.  Windows XP isn't a
>> guest we concentrate on, especially with device assignment.  Are you
>> using an AMD or Intel host system?  Does the same thing happen if you
>> run the XP guest on an IDE controller?  It would be helpful to post the
>> guest configuration, command line used or libvirt xml.  Also, you might
>> try latest upstream qemu-kvm to see if the problem still exists.
> 
> Maybe tracking of the INTx route across reset fails. Does this help?
> 
> diff --git a/hw/device-assignment.c b/hw/device-assignment.c
> index 7eeecad..0693141 100644
> --- a/hw/device-assignment.c
> +++ b/hw/device-assignment.c
> @@ -1719,6 +1719,8 @@ static void reset_assigned_device(DeviceState *dev)
>       * disconnected from the PCI bus. This avoids further DMA transfers.
>       */
>      assigned_dev_pci_write_config(pci_dev, PCI_COMMAND, 0, 2);
> +
> +    assign_irq(adev);
>  }
>  
>  static int assigned_initfn(struct PCIDevice *pci_dev)
> 

Nonsense, can't t make a difference as the PIIX3 resets the routing to
disable - which device-assignment does not deal with, but that's unrelated.

Try assigning a different slot to the passed-through adapter and the
lsi. For me it helped to put the lsi on one slot behind the
auto-assigned (-device lsi,addr=5).

I guess classic device assignment cannot support INTx sharing as the
kernel IRQ injection path does not inform user space about the device
state /wrt IRQs. Should be catch and reject this, or try to fix it up be
moving the assigned device around, Alex?

Jan

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