On Feb 7, 2013, at 1:46 PM, Vadim Rozenfeld wrote:
> On Thu, 2013-02-07 at 13:33 +0200, Michael S. Tsirkin wrote:
>> On Thu, Feb 07, 2013 at 09:53:39PM +1100, Vadim Rozenfeld wrote:
>>> On Thu, 2013-02-07 at 12:18 +0200, Michael S. Tsirkin wrote:
>>>> On Thu, Feb 07, 2013 at 08:24:10PM +1100, Vadim Rozenfeld wrote:
>>>>> On Thu, 2013-02-07 at 11:33 +1030, Rusty Russell wrote:
>>>>>> Vadim Rozenfeld <vrozenfe@xxxxxxxxxx> writes:
>>>>>>> On Tue, 2013-02-05 at 13:58 +0200, Michael S. Tsirkin wrote:
>>>>>>>> On Tue, Feb 05, 2013 at 03:45:38PM +0400, Michael Tokarev wrote:
>>>>>>>> Is it really
>>>>>>>>> that bad that the config space size changed? Why it has this effect?
>>>>>>> Because in this case it's hard to distinguish between resource's
>>>>>>> corruption and HW update.
>>>>>>
>>>>>> But it's also true that if we'd incremented revid you'd have the same
>>>>>> failure in this case, right?
>>>>>
>>>>> It depends. If we have explicitly specified revision id in inf file and
>>>>> this id doesn't mach the new revision id, Windows will not try to load
>>>>> the "incompatible" driver, and finish up with "device driver not found"
>>>>> dialog.
>>>>>
>>>>> Best regards,
>>>>> Vadim.
>>>>>
>>>>>>
>>>>>> Cheers,
>>>>>> Rusty.
>>>>
>>>> Well that's all in theory, in practice it does not look like revision ID
>>>> is specified in the NetKVM inf so this won't work?
>>>>
>>>> From what I see this inf specifies:
>>>>
>>>> NetKVM/wlh/netkvm.inf:%kvmnet6.DeviceDesc% = kvmnet6.ndi, PCI\VEN_1AF4&DEV_1000&SUBSYS_00011AF4
>>>> NetKVM/wxp/netkvm.inf:%kvmnet5.DeviceDesc% = kvmnet5.ndi, PCI\VEN_1AF4&DEV_1000&SUBSYS_00011AF4
>>>> NetKVM/wxp/netkvm2k.inf:%kvmnet5.DeviceDesc% = kvmnet5.ndi, PCI\VEN_1AF4&DEV_1000&SUBSYS_00011AF4
>>>>
>>>> So we can tweak any of vendor device and subsystem id.
>>>>
>>> Unfortunately, it won't. Only balloon has revision id, specified as a
>>> part of device HW descriptor. But it's only because virtio doesn't use
>>> revision ids. Otherwise it differential will be there.
>>
>> So your driver will load and attempt to work on rev=2 devices?
>
> All virtio-win drivers (net, serial, block, and scsi), except for
> balloon will.
>
>> If yes it's a bug. virtio spec specifies revision id as an ABI version.
>> Linux driver does:
>>
>> if (pci_dev->revision != VIRTIO_PCI_ABI_VERSION) {
>> printk(KERN_ERR "virtio_pci: expected ABI version %d, got %d\n",
>> VIRTIO_PCI_ABI_VERSION, pci_dev->revision);
>> return -ENODEV;
>> }
>>
We can add it from next release. Provided that everyone understand the consequences especially for boot devices (virtio-block and virtio-scsi).
>>
>>>>
>>>> Changing subsystem vendor ID actually will be completely
>>>> transparent to linux which for some reason looks at the
>>>> subsystem device ID (why? no idea) but not the subsystem vendor ID.
>>>> Of course this requires a valid vendor ID, getting this
>>>> costs $3000 I think.
>>>> We could tweak device ID too but that might break some other guests
>>>> which don't copy the crazy 'replace device id with subsystem device id'
>>>> logic from Linux.
>>>>
>>>
>>
>> Apropos, would you guys like to start to copy your patches to
>> virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx?
>> If you do, you might get some review and feedback, allowing
>> us to catch such forward compatibility issues earlier.
>>
>> Of course it's your project so entirely up to you.
>>
>>
>
>
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