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Macbook/Linksys wireless kernel hang solution

Shortly after getting my new macbook pro, I started to have issues with crashes where the kernel would hang and the display would freeze, requiring a power cycle/reboot. Calls to apple were basically useless. After futzing around I was able to diagnose the problem... I could provoke the problem by scp'ing a few large files. Some troubleshooting revealed that the macbook would hang only when I was using wireless, but if I plugged the ethernet cable in it was fine. I started mucking with settings in my Linksys "wireless-N" home router's advanced wifi settings and found one that stopped the macbook from crashing:

I disabled "frame burst" (which was enabled by default) and the problems completely disappeared.

I think the Mac is just dandy, but still it makes me think. I've been running a variant of Unix for the past 20 years. SCO Xenix, sysv 3.2, SVR4, Unixware, Dynix, sunos, Solaris, BSDI, Linux...and now OSX. 20 years, and we still have flaky drivers. 20 years, the industry still can't write a friggin driver that doesn't completely waste your machine if it sees a funny packet it doesn't parse right.

Update: That didn't fix it. I had to disable 'N' entirely in the router. That fixed it. See the comments for more details...

Comments (9)

Rich, if nothing else, thanks from the future. My wife REALLY wants a Mac next time, and we're using the same router @ home.

I wonder at the lineage of the drivers within OS X -- OS X is based on NeXT's OS, which in turn was built on a some Mach and SunOS, as I recall, which in turn was based on BSD 4.3, forked from SVr3(this part is hazy) from AT&T...I wonder what, deep down, is truly rewritten, and what is based on some pretty scalable stuff from when we were all in grade school.

"This is because the Mac OS X TCP/IP stack is largely a derivative of the FreeBSD stack" (from MacOS Internals by Singh)

Nice job on the debug. It was inspired to check the wireless vs. wired.

Kevin:

From all the problems I've seen with the 802.11n driver on the airport extreme cards, N is the wild west of the WiFi world.

The specs are a bit fuzzy, and honestly Apple seems to have put more work into putting a non certified spec card into the Pros than in doing some adequate QA work. I appreciate the ahead of schedule preview of the N technology, but it really shouldn't be this much trouble.

I ended up just breaking down and buying an Airport Extreme Base Station to get around all the issues I was having.

Thanks Kevin. I've continued to have the occaisonal crash. I've disabled "N" in my wifi router ("B and G only option"). Will see if that helps... I'm NOT going to buy an Airport just to coddle this thing. :)

Hi Rich,

Thanks very much for figuring this out. I had given up on using the wireless in my new MacBookPro! I was thinking that I'd have to reinstall the OS or something.

I've adjusted the settings as you suggested in the LinkSys WRT350N and will see how long the MacBookPro works without a crash. So far so good after an hour with over 1.5 GB downloaded as a test.

Without the settings it was usually an hour or so before it crashed with an error in the IOKit. Have you reported this problem to Apple yet?

Thanks again...

Peter

Zach:

Yea I've been dealing with this problem on my Macbook Pro for the past few weeks... Was rather anxious once I found this page... unfortunately deactivating that option in the router settings did NOT solve the issue for me... my MBP froze just like it always did... My solution to the problem was simply to deactivate "Wireless N" mode on my router and stick with "Wireless G." The Support Specialist I spoke with from Apple explained that the WRT350N doesn't look to be compatible with 802.11n "Draft 2," which is what the Macbook Pro's Airport card is compatible with... So it's pretty much all Linksys's fault.

Thanks for the post, even though your solution didn't entirely work it got me thinking... I checked out Linksys's site for firmware updates, and they just recently released an update. Version 1.01.9 updates the router to Draft 802.11n version 2.0. I just installed it... no problems yet. Plus, surprisingly, the speed has dramatically increased. I'll comment again later to confirm the update fixed my problem.

I always thought this problem was with my Mac because it only started happening after I paid the $1.99 to update the card so it would support N. I never imagined that the router could cause the mac to actually freeze.

Richard:

Thanks for the update Cliff... but I can't find that update on the Linksys site. Can you please give us a link?

Anon:

Thanks for the tip. I've been having similar problems with a MacBook Pro and a NETGEAR ProSafe VPN Wireless ADSL Gateway DGFV338. Having disabled the advanced G settings seems to have solved things.

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