Re: [PATCH] Revert "cfg80211: make WEXT compatibility unselectable"

From: Arend van Spriel
Date: Wed Dec 31 2014 - 15:32:30 EST

On 12/31/14 18:31, Theodore Ts'o wrote:
On Wed, Dec 31, 2014 at 04:02:24PM +0100, Arend van Spriel wrote:

It is unfortunately indeed. I think iwconfig and friends will never go away
although iw is a better alternative, simply because people don't like to
change their home-made scripts/tools. WIRELESS_EXT actually is largely, but
not entirely, gone in upstream drivers and what we are talking about here is
CFG80211_WEXT which allows WEXT userspace to interact with cfg80211-based
drivers through a compatibility layer.

Most poeple are still using "route" and "ifconfig" instead of "ip".
Deal with it. Personally, I find it much easier to use the existing
commands instead of figuring all of the various subcommands, and the
options to the subcommands to commands like "ip" and "iw". At least
"ip help route" will give me all of the options to "ip route", where
as "iw help phy" doesn't tell give me the options; instead I have to
paw through 300 lines of "iw help" in order to find the command I
need. So having a better user interface / help system so people can
better understand how to use iw would be a great step forward.

Agree. I can't even recall using "ip" ever. iw help system does provide command specific help. The phy keyword is both a command and a selector key, which I realize is confusing to the user, eg. 'iw help info' does provide help for the 'info' subcommand.

Better yet, why not hack into the "iw" command backwards compatibility
so that if argv[0] is "iwlist" or "iwconfig", it provides the limited
subset compatibility to the legacy commands. Then all you need to do
is to convince the distributions to set up the packaging rules so that
"iw" conflicts with wireless-tools, and you will be able to get
everyone switched over to iw after at least seven years.

Thanks. If there are still drivers, upstream or out-of-tree, providing only WEXT API this will not work unless iwconfig/iwlist can distinguish those from cfg80211-based drivers (which is possible) and fallback to WEXT ioctl syscalls. Just not sure if it is worth the effort. As you stated below, it does not seem "evil" to retain WEXT if that is providing users what they need.


Note that I said *seven* years --- there are people who try to use an
enterprise kernel, or an older Debian Stable or Ubuntu LTS userspace,
with a newer kernel, and and if said users notice, and complain, Linus
*will* revert the commit. (Note that I've worked at more than one
company where I was forced to use an older Ubuntu LTS or RHEL distro
if I wanted to connect to the intranet, and I was using bleeding edge
kernels --- and if anything like that had broken, I would have
complained directly to Linus, cc'ing the patch author and the wireless
maintainers with the revert. And while I fortunately am not trying to
do upstream development with a stable distro, be sure there are other
such folks around who have to live with similar restrictions.)

- Ted

P.S. If you really think it's evil that users use the
simpler-to-understand iwconfig/iwlist interface over the iw command
line interface, if you provide full backwards compatibility for the
iwconfig/iwlist commands so you can "take over" from wireless-tools,
you could even have a mode which, in addition to doing what the user
wants, prints a "by the way, here's the equivalent if you want to use
the iw command instead". I don't see the reason of allowing users to
continue to use iwconfig and iwlist, though --- face it, route and
ifconfig are going to be around for a long time; why not let users use
iwconfig and iwlist if it's sufficient for their needs?

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