Subject: Re: Where Linux 802.11x support needs work

From: Roar Bjørgum Rotvik <[email-masked]>
Date: Wed, 26 Jan 2005 08:31:35 +0100

Michael Wu wrote:
> On Tuesday 25 January 2005 11:03 pm, Dan Williams wrote:
> 
>>> One of the big item not mentionned by you is the in-kernel
>>>802.11 stack (native frames and management). If done right, I guess it
>>>would mostly be transparent to you...
>>
>>You know, I was thinking of it and I just forgot to put it on the list.
>>If you're including madwifi and ipw2x00, we have a grand total of what, 3
>>or 4 802.11 stacks in the kernel at the same time?  (madwifi,
>>orinoco/hermes, ipw2x00, linux-wlan-ng)
>>
> 
> Only orinoco/hermes is in the kernel, and that doesn't really have much of an 
> 802.11 stack, since most things are done in hardware. Madwifi has a fairly 
> complete 802.11 stack (ported from netbsd), and so does adm8211. Dunno about 
> ipw2x00.

Do any of these 80.11 stacks (or the upstream linux network stack) have 
a solution for WLAN cards with 802.11e (QoS extension) with more than 
one HW/firmware transmit queues?

As you may or may not know WLAN cards implementing 802.11e may have more 
than one HW/firmware transmit queue (I know of an 802.11a chip with 
802.11e extension that have 4 transmit queues in hardware/firmware with 
different priority).

As far as I know the linux network stack today only have one qdisc queue 
pr. device (struct netdev), so the driver may only stop/start 
(netif_stop_queue()/netif_wake_queue()) one queue at a time. This is a 
problem for drivers with more than one HW/firmware transmit queues, as 
you can not let a full low priority HW queue block the netdev queue.

Is there an existing solution for this problem, or is an 
multiqueue-pr-device solution being planned as part of introducing a 
common 802.11 stack in the kernel?

-- 
Roar B. Rotvik