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From: Alexander Duyck <alexander.h.duyck@intel.com>
To: David Laight <David.Laight@ACULAB.COM>
Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com>,
	davem@davemloft.net, Tushar Dave <tushar.n.dave@intel.com>,
	netdev@vger.kernel.org, gospo@redhat.com, sassmann@redhat.com
Subject: Re: [net-next 1/8] e1000e: Minimum packet size must be 17 bytes
Date: Tue, 23 Oct 2012 09:37:08 -0700	[thread overview]
Message-ID: <5086C7B4.6060202@intel.com> (raw)
In-Reply-To: <AE90C24D6B3A694183C094C60CF0A2F6026B705D@saturn3.aculab.com>

On 10/23/2012 08:25 AM, David Laight wrote:
>> This is a HW requirement. Although a buffer as short as 1 byte is allowed,
>> the total length of packet before, padding and CRC insertion, must be at
>> least 17 bytes.  So pad all small packets manually up to 17 bytes before
>> delivering them to HW.
> Where do such very short packets come from?
> The shortest one I know of have:
>  6 bytes dest-mac
>  6 bytes src-mac
>  2 bytes length
>  3 bytes llc header (eg reflect request).
> 17 bytes total.
>
> 	David
>

This mostly has to do with security fuzz testers sending raw packets at
the interface trying to see what can cause it to hang.  As far as I know
nothing from the stack will be that small, but we still have to support
raw packets that size.

Thanks,

Alex

  reply	other threads:[~2012-10-23 17:07 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-10-23 10:24 [net-next 0/8][pull request] Intel Wired LAN Driver Updates Jeff Kirsher
2012-10-23 10:24 ` [net-next 1/8] e1000e: Minimum packet size must be 17 bytes Jeff Kirsher
2012-10-23 15:25   ` David Laight
2012-10-23 16:37     ` Alexander Duyck [this message]
2012-10-23 10:24 ` [net-next 2/8] maintainers: update with official intel support link, new maintainer Jeff Kirsher
2012-10-23 13:25   ` Joe Perches
2012-10-24  4:32     ` Jeff Kirsher
2012-10-24  4:52       ` Joe Perches
2012-10-24  5:13         ` Jeff Kirsher
2012-10-24 17:31       ` Rick Jones
2012-10-23 10:24 ` [net-next 3/8] igb: Update get cable length function for i210/i211 Jeff Kirsher
2012-10-23 10:24 ` [net-next 4/8] igb: Update version Jeff Kirsher
2012-10-23 10:24 ` [net-next 5/8] ixgbevf: make netif_napi_add and netif_napi_del symmetric Jeff Kirsher
2012-10-23 10:24 ` [net-next 6/8] ixgbevf: Check for error on dma_map_single call Jeff Kirsher
2012-10-23 10:24 ` [net-next 7/8] ixgbevf: fix softirq-safe to unsafe splat on internal mbx_lock Jeff Kirsher
2012-10-23 10:24 ` [net-next 8/8] ixgbevf: Update version string Jeff Kirsher
2012-10-23 17:28 ` [net-next 0/8][pull request] Intel Wired LAN Driver Updates David Miller

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