[Xen-devel] RE: [Xci-devel] Porblem with disabling and then re-enabling a PT device in Windows

[Kamala Narasimhan <Kamala.Narasimhan@xxxxxxxxxx>]

There is a chance pciback is changing the bit you are referring to.  To confirm 
that, just for testing purpose you might want to avoid FLR for that device or 
simply not build pciback or comment out relevant code in that module whichever 
is easier and see if that helps.  If it does, you can then look into fixing the 
problem the right way.

Kamala

> -----Original Message-----
> From: xci-devel-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xci-devel-
> bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Tom Rotenberg
> Sent: Wednesday, November 25, 2009 8:09 AM
> To: xen-devel@xxxxxxxxxxxxxxxxxxx; xci-devel@xxxxxxxxxxxxxxxxxxx
> Subject: [Xci-devel] Porblem with disabling and then re-enabling a PT
> device in Windows
> 
> Hi All,
> 
> (This is a continuation to my previous mail, but since it looks like a
> different problem - i decided to open a new thread for it)
> 
> ----
> Problem Description:
> ----
> I am doing pass-through of an Intel wireless LAN device to a Windows
> XP domU (my machine is Dell e6400), and it looks like it's working ok.
> Then, i disable the device using Windows device manager, and the
> device is now disabled, after that i re-enable the device, and Windows
> re-enables the device correctly. However, the wlan device seems to
> malfunction (it can't turn on the WiFi of the computer), and can't
> connect to wireless networks.
> I tried it, both with MSI translation on, and with MSI translation off
> - it doesn't matter.
> 
> ----
> My analysis:
> ----
> 1) Well, taking a look at the real PCI config space, before disable
> and after the (last) enable, shows that the difference is at the Intx
> bit (read-only bit 3 at status register (offset 0x6) at the PCI config
> space). Before disable, that bit was 0, and after the last enable that
> bit was 1.
> This, according to my understanding, means that the device is
> asserting it's IntX , and probably waiting for someone to handle it,
> no?
> 
> 2) When i tried to track when did this bit was changed - i added a
> code which in every PCI config read, checks if that bit was changed -
> and added a print when it changed. The proper lines in the qemu log
> looks like this:
> ...
> pt_pci_read_config: [00:01.0]: address=00f0 val=0x00000000 len=2
> ACPI PCI hotplug: read addr=0x10c6, val=0x0f.
> ACPI PCI hotplug: read addr=0x10c6, val=0x0f.
> pt_pci_read_config: TEST CODE: STATUS CHNAGED! OLD: 0x10, NEW: 0x18
> pt_pci_read_config: [00:01.0]: address=0000 val=0x00008086 len=2
> ...
> 
> This implies that the bit was changed, about the same time that
> Windows tried to start using it (because, i assume that it tried using
> it, just after questioning the ACPI for the existence of the device).
> No?
> 
> 
> Can someone help me with this?
> 
> (BTW - i am using Xen 3.4)
> 
> Tom
> 
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