Re: [Qemu-discuss] How to resolve "Failed to mmap" error?

[A223 A223]

On Thu, Oct 6, 2016 at 8:30 PM, A223 A223 <address@hidden> wrote:
> On Thu, Oct 6, 2016 at 9:46 AM, Alex Williamson
> <address@hidden> wrote:
>> On Wed, 5 Oct 2016 20:30:34 -0700
>> A223 A223 <address@hidden> wrote:
>>
>>> On Wed, Oct 5, 2016 at 9:33 AM, Alex Williamson
>>> <address@hidden> wrote:
>>> > On Wed, 5 Oct 2016 02:13:21 -0700
>>> > A223 A223 <address@hidden> wrote:
>>> >> How can I go about tracking down the root cause of this error?
>>> >
>>> > This often means that the device resources are in use by another,
>>> > non-pci driver.  Look in /proc/iomem and /proc/ioport to see if any
>>> > drivers are claiming sub-regions on the device.  You can also turn on
>>> > tracing and look for the event vfio_region_mmap_fault, which might give
>>> > us more information (see docs/tracing.txt).  Also, please provide 'sudo
>>> > lspci -vvvs 5:00.0' so we can see the device resources.  Thanks,
>>>
>>> The simpletrace output wouldn't parse for me using the python script
>>> (I'll paste the trace at the end of this email), so I used the ftrace
>>> backend instead (
>>> https://drive.google.com/open?id=0Bwjufq6oAZMfMVpUYTUxODR0NW8 ). It's
>>> quite large and I'm not sure what I'm looking for, so I didn't look at
>>> it very carefully.
>>
>> That's not the right trace, that's like kvm trace or something.  Try:
>>
>> # ./configure --enable-trace-backends=log
>>
>> # echo vfio_region_mmap_fault > events.txt
>>
>> Then add to your qemu commandline "-trace events=events.txt".  You
>> should get maybe a couple extra log lines per boot, not gobs of output.
>
> Ah, got it. Here are the relevant log lines then:
>
> address@hidden:vfio_region_mmap_fault Region 0000:05:00.0 BAR
> 2 mmaps[0], [20000000000 - 1ffffffffff], fault: -22
> qemu-system-x86_64: -device
> vfio-pci,host=05:00.0,bus=root.1,addr=00.5: Failed to mmap
> 0000:05:00.0 BAR 2. Performance may be slow

I took a look at everything again and noted this in the lspci output
for the Fresco Logic USB controller:
Vector table: BAR=2 offset=00000000
PBA: BAR=4 offset=00000000

Is it normal for both the Vector table and PBA to have a 0 offset?

Thanks,
Andrew