netdev - Re: is "volatile" the cause of ifconfig flags not matching sysfs flags?

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Date:   Thu, 23 Aug 2018 07:50:38 -0400 (EDT)
From:   "Robert P. J. Day" <rpjday@...shcourse.ca>
To:     Stephen Hemminger <stephen@...workplumber.org>
cc:     Linux kernel netdev mailing list <netdev@...r.kernel.org>
Subject: Re: is "volatile" the cause of ifconfig flags not matching sysfs
 flags?

On Wed, 22 Aug 2018, Stephen Hemminger wrote:

> On Wed, 22 Aug 2018 18:32:36 -0400 (EDT)
> "Robert P. J. Day" <rpjday@...shcourse.ca> wrote:
>
> >   almost certainly another dumb question, but i was poking around the
> > sysfs, particularly /sys/class/net/<ifname>/*, to familiarize myself
> > with what i can glean (or set) re interfaces under /sys, and i noticed
> > "flags", but what i get there doesn't match what i get by running
> > ifconfig.
> >
> >   specifically, if i list the flags for my wireless interface under
> > /sys:
> >
> > $ cat flags
> > 0x1003
> > $
> >
> >   but with ifconfig:
> >
> > $ ifconfig wlp2s0
> > wlp2s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
> >               ^^^^
> >
> >   do those two "flags" values represent the same set of flags? and
> > does the obvious difference have to do with some of those flags being
> > "volatile" as dewscribed in include/uapi/linux/if.h? or am i just
> > totally misreading this?
> >
> > rday
> >
>
> sysfs reports netdevice->if_flags where as ifconfig is getting hex
> value from SIOCGIFFLAGS which does:
> 	dev_get_flags(dev)
>
> The value in sysfs is more intended for internal debugging, where
> all the normal userspace API's return a more limited set of
> historical values.

  so the history aside, those values ultimately represent the same
flags?

rday

-- 

========================================================================
Robert P. J. Day                                 Ottawa, Ontario, CANADA
                  http://crashcourse.ca/dokuwiki

Twitter:                                       http://twitter.com/rpjday
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