SKB BUG: Invalid truesize

Sylvain fricompte
Mon Mar 9 03:09:14 PDT 2009

On 03/09/2009 05:12 PM, Jouni Malinen wrote:
 > On Mon, Mar 09, 2009 at 02:16:03PM +0800, Sylvain wrote:
 >> I just reported this bug at Ubuntu:
 > That bug is about 2.6.20 and was filed almost two years ago.. Are you
 > sure the issue you are seeing is for the same problem?

I am sure I am getting the same error message. As for what causes it, 
the initial report was not exactly full of details... so it is hard to 

 > Would it be possible for you to test this with a more recent kernel
 > version or well, something that is closer to mainline development
 > kernels. The warning in skbuff.c is from code that does not seem to
 > exist in the current kernel development tree and as such, may only
 > interest people who happen to be working with that distro kernel tree.

Unfortunately, the Ubuntu guys decided to stick with 2.6.28 for their 
next release due on April. As I said, I really enjoy the deb/apt-get 
convenience so I will stick to it as long as possible.

 > The SKB truesize issue should have nothing to do with hostapd, i.e., it
 > is a kernel side problem. However, since the current wireless-testing
 > git tree does not seem to have code that would generate such a warning,
 > it may be more difficult to find people interesting in researching this
 > with the old/distro version of the kernel.

I understand that this is the kernel that barks about this issue, but 
since it seems to be caused by the hostapd/kernel interaction, I thought 
it would make sense to report this to this list. My apologies if it was 
not such a good idea... I'm sorry if my feedback was of no value to you. 
On the bright side, maybe my experience will benefit to the few Ubuntu 
users who intend to use hostapd.

 >> Bonus question: the chip is supposed to support draft n, but
 >> 1/ iw list shows 54.0 Mbps as the highest bitrate
 > Update iw and you'll get list of supported MCS indexes (0..15) for HT
 > rates.

$ iw --version
iw version 0.9.9-nogit
As far as I can tell, my iw is up to date. Did you mean I should use the 
git version or something?

 >> 2/ on my eee pc, "iwlist ra0 scan" lists my AP with Bit Rates:118 Mb/s
 >> Who is right, and what should I do to use the chip at its maximum speed?
 > It was probably already running at maximum speed. However, you should
 > probably update hostapd and kernel to the latest development snapshots
 > to get some of the recent bug fixes for AP mode operations.

Okey, well, I already updated hostapd to 0.6.8 thanks to Per 
Hermansson's PPA. It seems that it fixed my SKB BUG problem. If this is 
confirmed, I am a happy happy guy.

Thank you very much for your fast and detailed reply.


PS to Jouni: sorry for the double mail...

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