On 6/6/19 13:45, Adam Williamson wrote:
On Thu, 2019-06-06 at 11:15 -0600, Chris Murphy wrote:
> On Thu, Jun 6, 2019 at 9:49 AM Richard Ryniker <ryniker(a)alum.mit.edu> wrote:
>> I think you will find the file is not truly empty. /sys is not an actual
>> file system, merely an interface to kernel information. There is no
>> directory structure that records the length or other attributes of a file,
>> as is the case for data on real media such as disks.
>>
>> If you read the /sys/kernel/debug/usb/devices file, you should find the
>> data you seek.
>
> [root@fmac ~]# ls -l /sys/kernel/debug/usb/devices
> -r--r--r--. 1 root root 0 Jun 6 10:11 /sys/kernel/debug/usb/devices
> [root@fmac ~]# cat /sys/kernel/debug/usb/devices
> cat: /sys/kernel/debug/usb/devices: Operation not permitted
> [root@fmac ~]#
>
> 5.2.0-0.rc3.git1.1.fc31.x86_64
Try it with enforcing=0 ?
I just tried permissive mode with the same result. I've just looked
through of the "files" in debug and they are all empty; so I'm guessing
that the kernel folks turned this off.
That's okay, it was a reach given how things have been changing and I
wouldn't want to be running in permissive mode to get the info. I hear
there is a new interface to get information on connected USB devices
that ordinary users can access. I think I will investigate that. Who
knows, I may end up writing a little code that someone else might find
useful.
Thanks everyone for trying to help.
Have a Great Day!
Pat (tablepc)