Alfa USB wireless card stopping working, then kernel panic

Jethryn Freyman · Dec 11, 2011

So, I have a Power Mac running Leopard, and for internet I use an Alfa AWUS036H USB wireless adapter. It's far better than the Airport Extreme card, much better performance and it doesn't drop out. I've never had problems with this card before, although I've also never used it as my primary wireless card before. Using Ethernet isn't an option.

Anyway, once every fortnight or so, I'll lose all network connectivity. Either the green light on the wireless card will stay on, or it'll stay off. Using the Realtek utility software to switch the radio on or off shows no effect, and it shows 0% signal strength where normally it shows 70-80%.

Nothing can get the card working again, and when I pull the USB cable out, I get a kernel panic. Nothing I can do about it. I've tried unloading the kernel extension before pulling the plug, but that doesn't work (can't remember the error message, I think it said I didn't have permission, despite running the command as root.)

The kernel panic reports look like one of the following:

Code:

panic(cpu 0 caller 0x000ACF54): enable_preemption: preemption_level -1

Latest stack backtrace for cpu 0:
      Backtrace:
         0x0009CC88 0x0009D63C 0x00029DA0 0x000ACF54 0x00C63780 0x00C66048 0x00C661F0 0x00C64B70 
         0x00C60F6C 0x00C61E34 0x00344D70 0x0035B9D0 0x0034B888 0x0034BB80 0x0034C390 0x0050E990 
         0x00C2DADC 0x00C303A4 0x00C2E608 0x00C2E3A0 0x0003F2A0 0x000B1DD4 
      Kernel loadable modules in backtrace (with dependencies):
         com.realtek.driver.RTL8187(1.0)@0xc5e000->0xcdbfff
            dependency: com.apple.iokit.IONetworkingFamily(1.6.1)@0x9e2000
            dependency: com.apple.iokit.IOUSBFamily(3.5.2)@0x4fd000
         com.apple.driver.AppleUSBHub(3.4.9)@0xc25000->0xc34fff
            dependency: com.apple.iokit.IOUSBFamily(3.5.2)@0x4fd000
         com.apple.iokit.IOUSBFamily(3.5.2)@0x4fd000->0x533fff
Proceeding back via exception chain:
   Exception state (sv=0x54fd7c80)
      PC=0x00000000; MSR=0x0000D030; DAR=0x00000000; DSISR=0x00000000; LR=0x00000000; R1=0x00000000; XCP=0x00000000 (Unknown)

BSD process name corresponding to current thread: kernel_task

Code:

panic(cpu 0 caller 0x000ACF54): enable_preemption: preemption_level -1

Latest stack backtrace for cpu 0:
      Backtrace:
         0xF704C6EC 
         backtrace terminated - unaligned frame address: 0x939190A3

Proceeding back via exception chain:
   Exception state (sv=0x6711fc80)
      PC=0x00000000; MSR=0x0000D030; DAR=0x00000000; DSISR=0x00000000; LR=0x00000000; R1=0x00000000; XCP=0x00000000 (Unknown)

BSD process name corresponding to current thread: Unknown

Any thoughts?

thorns · Dec 12, 2011

I use the same adapter and have the exact same problem from time to time. No idea what causes it. Sometimes I can reattach the adapter without getting a kernel panic, but that's about it.

Jethryn Freyman · Dec 12, 2011

thorns said:
I use the same adapter and have the exact same problem from time to time. No idea what causes it. Sometimes I can reattach the adapter without getting a kernel panic, but that's about it.

Yeah I heard a bit about some instability with this card but didn't believe it at the time because I hadn't been using it full time for very long. For the moment I've switched over to a USB dongle with an rt73 chip in it, good performance so far, we'll see how stability goes...

zen.state · Dec 12, 2011

Kernel panic = hardware error/failure and nothing else.

The errors are right there to read and see the problem. This is clearly an issue:

com.realtek.driver.RTL8187(1.0)@0xc5e000->0xcdbfff

If you want those errors to stop then you need to stop using that hardware. I also don't understand people that use wifi on a desktop. I think you're expecting some miracle solution?

Bloodstar · Dec 12, 2011

zen.state said:
If you want those errors to stop then you need to stop using that hardware. I also don't understand people that use wifi on a desktop. I think you're expecting some miracle solution?

Speaking from some experience, sometimes it's easier than running ethernet cables around - my router is in one room, and one desktop is relatively far away from it, so I was using wireless on it for a while. If there are a lot of computers in a house that aren't nearby the router, this could remove a lot of worry about wiring things around or having to move things to get the wire in place.

Of course, that USB adapter sucked, so I ended up getting an ethernet cable for it anyway (which is much better of an idea now, as the thing's now running Linux, meaning I'd have to screw around with drivers EVERY TIME the thing booted... the thing's drivers also hosed the XP install on it, I'm getting the feeling.)

Certainly wouldn't use wireless if the desktop was nearby the router, though. (My C2D Windows tower, MDD, and server have always run on wired connections.)

Jethryn Freyman · Dec 12, 2011

zen.state said:
Kernel panic = hardware error/failure and nothing else.

True..

I also don't understand people that use wifi on a desktop.?

I stated Ethernet wasn't an option; the router is just too far away.

wrinkster22 · Dec 12, 2011

Jethryn Freyman said:
True..

I stated Ethernet wasn't an option; the router is just too far away.

Get an airport express and airport extreme.
The airport express can to wifi to ethernet.

zen.state · Dec 12, 2011

Jethryn Freyman said:
I stated Ethernet wasn't an option; the router is just too far away.

If you happen to own your home maybe wiring it to key rooms with cat6 would be a good idea. That way you would have an ethernet plug on the wall in your computer room.Faster and far far more secure.

Nameci · Dec 12, 2011

I do agree with you zen, faster and more reliable connectivity.

thorns · Dec 13, 2011

zen.state said:
If you want those errors to stop then you need to stop using that hardware. I also don't understand people that use wifi on a desktop. I think you're expecting some miracle solution?

How is it any different from using wifi on a mobile computer? I think everyone will agree that a fixed ethernet connection would be more reliable, but sometimes physical circumstances won't allow a wired soultion. That's just how it is and I can't see anything wrong with it.

zen.state · Dec 13, 2011

thorns said:
How is it any different from using wifi on a mobile computer? I think everyone will agree that a fixed ethernet connection would be more reliable, but sometimes physical circumstances won't allow a wired soultion. That's just how it is and I can't see anything wrong with it.

It's not really that there is anything wrong with using wifi. If it's just for internet then it makes more sense but it can never offer the security and reliability a wire can give.

When it comes to network file sharing even the fastest wifi can't compete with the performance of gigabit ethernet. I personally don't use wifi at all.

vohdoun · Dec 14, 2011

zen.state said:
I also don't understand people that use wifi on a desktop.

It's a bit hard not to when the router is in another room and don't want ethernet cables lying across the floor for people to trip up on and/or going across/up walls looking a mess.

Jethryn Freyman · Dec 14, 2011

vohdoun said:
It's a bit hard not to when the router is in another room and don't want ethernet cables lying across the floor for people to trip up on and/or going across/up walls looking a mess.

This, I don't really have a choice.

Anyway, the RT73 stick was quite cheap and sucked, so I'm back to the iffy Alfa card. I think I can just shut down if it goes faulty, I can deal with that for now. It's not like it happens all the time, and Ethernet is NO option at all right now.

vohdoun · Dec 14, 2011

I'd recommend this... http://www.edimax.com/en/produce_detail.php?pd_id=277&pl1_id=1&pl2_id=44

Nearly been using it a month.

Jethryn Freyman said:
and Ethernet is NO option at all right now.

I'm in the same boat with this PowerMac. It's not an issue though. Nor am I going to fit ethernet wall plugs as it's not a room that is permanent with the computer even though the PC shares the wireless connection through the ethernet port.

I do have other Cat6 routed in the router room with trunking into the attic through to the living room for CCTV and Sky Digital since they're permanent places.

However, I'm not saying I wont fit ethernet sockets to the walls in the future. I'd also need to get a ethernet switch which is not something a must do right now.

zen.state said:
I also don't understand people that use wifi on a desktop.

Most people don't when they don't know the story and reasons.

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Alfa USB wireless card stopping working, then kernel panic

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