[systemd-devel] udev_device_get_driver implementation

[Greg KH]

A: http://en.wikipedia.org/wiki/Top_post
Q: Were do I find info about this thing called top-posting?
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http://daringfireball.net/2007/07/on_top

On Wed, Apr 24, 2019 at 11:58:08AM -0700, Sayeed hyder wrote:
>  ll
> /sys/devices/LNXSYSTM:00/device:00/ACPI0012:00/ndbus0/region1/pfn1.1/block/pmem1/
> total 0
> -r--r--r-- 1 root root 4096 Apr 19 09:38 alignment_offset
> -rw-r--r-- 1 root root 4096 Apr 19 09:38 badblocks
> lrwxrwxrwx 1 root root    0 Apr 19 09:38 bdi ->
> ../../../../../../../../virtual/bdi/259:3
> -r--r--r-- 1 root root 4096 Apr 19 09:38 capability
> drwxr-xr-x 2 root root    0 Apr 19 09:38 dax
> -r--r--r-- 1 root root 4096 Apr 19 09:38 dev
> lrwxrwxrwx 1 root root    0 Apr 19 09:38 device -> ../../../pfn1.1
> -r--r--r-- 1 root root 4096 Apr 19 09:38 discard_alignment
> -r--r--r-- 1 root root 4096 Apr 19 09:38 ext_range
> drwxr-xr-x 2 root root    0 Apr 19 09:38 holders
> -r--r--r-- 1 root root 4096 Apr 19 09:38 inflight
> drwxr-xr-x 2 root root    0 Apr 19 09:38 power
> drwxr-xr-x 2 root root    0 Apr 19 09:38 queue
> -r--r--r-- 1 root root 4096 Apr 19 09:38 range
> -r--r--r-- 1 root root 4096 Apr 19 09:38 removable
> -r--r--r-- 1 root root 4096 Apr 19 09:38 ro
> -r--r--r-- 1 root root 4096 Apr 19 09:38 size
> drwxr-xr-x 2 root root    0 Apr 19 09:38 slaves
> -r--r--r-- 1 root root 4096 Apr 19 09:38 stat
> lrwxrwxrwx 1 root root    0 Apr 19 09:38 subsystem ->
> ../../../../../../../../../class/block
> drwxr-xr-x 2 root root    0 Apr 19 09:38 trace
> -rw-r--r-- 1 root root 4096 Apr 19 09:38 uevent

As suspected, that is a class device (it is a block device), and a class
device does not have a direct "driver" bound to it.  If you want to find
the "real" driver for the device, go to 'device' and find it, right?

Ah, but this might be a mess, with a child device.  DAX stuff is odd, I
would recommend going and asking those kernel developers what they were
thinking when they added a sub-device here :(

good luck!

greg k-h