netdev - ixgbe: Question about Flow Control on 10G

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <543D72FE.9090107@citrix.com>
Date:	Tue, 14 Oct 2014 12:01:18 -0700
From:	dom <dominic.curran@...rix.com>
To:	<donald.c.skidmore@...el.com>, <netdev@...r.kernel.org>
Subject: ixgbe: Question about Flow Control on 10G

Hi

I have a question about the ixgbe driver's handling of 'ethtool -a ethX' 
when the NIC is using fibre.

Specifically I don't understand the code introduced by this commit:

commit 73d80953dfd1d5a92948005798c857c311c2834b
Author: Don Skidmore <donald.c.skidmore@...el.com>
Date:   Wed Jul 31 02:19:24 2013 +0000
Subject: ixgbe: fix fc autoneg ethtool reporting.

The function introduced the function:
        ixgbe_device_supports_autoneg_fc()

which gets called by ixgbe_get_pauseparam()/ixgbe_set_pauseparam().

specifically there is a  case in ixgbe_device_supports_autoneg_fc()

     case ixgbe_media_type_fiber_qsfp:
     case ixgbe_media_type_fiber:
         hw->mac.ops.check_link(hw, &speed, &link_up, false);
         /* if link is down, assume supported */
         if (link_up)
             supported = speed == IXGBE_LINK_SPEED_1GB_FULL ?
                 true : false;

If link_up=1 then why is supported only true for a 
speed=IXGBE_LINK_SPEED_1GB_FULL ?

Why is Flow Control not  supported for IXGBE_LINK_SPEED_10GB_FULL ?

I have search through the 82599 spec, but I can't find a reason.
Please can anyone help me understand ?

Thanks
dom
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html