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Ongoing fatal crash and security bug related to connecting external display

The infrastructures in OS X to resume from sleep, to authenticate, and to change displays is fundamentally not working.

The security bug I have encountered has to do with connecting a cinema display exclusively to a MacBook Pro. This is a specific situation, but please note that I have experienced the same problem on no fewer than three independent laptop. Plus, the Genius in the Apple Retail Store was convinced of the general instability of this infrastructure. The security problem is that hot corners no longer function if I transition between two states in the same reboot. The first state is where I have the laptop powered on and using its own internal display exclusively (when I'm on the road). The second state is when I have the laptop displaying its output exclusively on an external display (when I'm at home). What happens is that an attempt to use hot corners fails. There is no response. I even added configuration on all four corners (whereas I originally had settings only for the rightmost corners), and even then, the hot corner action (of sleeping the display or entering locked screen saver mode) does not commence. This prevents the user from being able to secure the display on demand using standard methods that are supposed to work.

The instability level related to connecting the external display exclusively is high. Again, I've experienced this on no fewer than three independent laptops, and the Apple Genius at the Retail Store confirmed that this aspect of OS X did not work consistently. When I want to connect the cinema display to the laptop in such a way that the laptop's own display is not part of the active screen, the process I use succeeds about half the time. Supposing I have been on the road, where I am using the laptop display exclusively. I then put the laptop to sleep. When I return home with the lid open, I connect first the USB (power) from the cinema display to the laptop, and then I connect the Mini DisplayPort. When that step works, what happens is that the login screen shows on the cinema display despite the fact that my laptop lid is closed. This is good, and is what I want. At that point, I open the laptop lid and quickly log in.

With Apple being a mobile device company, I rely on the laptop for tasks that one traditionally may use a desktop for. This simply points to the versatility of the laptop. But I'd like the bugs resolved, so that I do not have to hesitate to make use of the inherent flexibility possible with the MacBook Pro.

Here's what happens when the process (of connecting the external display in a way that establishes itself as the only screen in use by OS X) fails. Firstly, when I connect the external display via Mini DisplayPort, the laptop doesn't even respond. Instead, it remains asleep. So to work around it I have to repeatedly disconnect and reconnect the Mini DisplayPort so that the asleep MacBook Pro will see that there is a display connected to it. Also, sometimes that isn't even enough and I have to open the laptop lid, and put it to sleep again so as to trigger whatever actions are necessary to recognise the external display (presumably by having the laptop recently awake). Around half the time, I have to play this game of disconnecting and reconnecting until it actually works. This high level of reproducibility (confirmed by the Apple Genius representative's confidence that this part of the system doesn't actually work) should make it easy for an engineer to look into the problem.

Fatally, and recently, OS X has completely crashed when I have attempted to connect the external display. The external display has gone completely blue, and after a half a minute, it blanked out and my entire laptop became unresponsive. I called Apple Support and was given a case number. I also took the laptop into the retail store to see if I could recover my current session without rebooting. There was no process suggested to make that happen and I was told to reboot the machine. I've had this happen before on other laptops, and it is frustrating that the kernel reaches such a state that it cannot be used. As I see it, this problem is not too unrelated to the way that I need to play a game in order to get the external display connected exclusively. Here are some workarounds that could be added:

Firstly, whenever I connect an external display, I'd like the laptop to see that this has happened, and to take action accordingly (such as resuming from sleep). Secondly, If I connect an external keyboard, and press a key on it, I'd like this to wake the laptop too (in the event that the first method fails for some unforeseen reason). I'd also like the connection of the cinema display's USB power not to cause the laptop to enter into a confused state between asleep and awake. Sometimes I need to disconnect and reconnect USB power in order to trigger the laptop into waking, but that's only because it's not doing it on its own properly. On the other hand, I also ensure that the laptop doesn't have the Mini DisplayPort connected without also having the cinema display USB power connected, because that also is an unsupported configuration.

I've also gotten the laptop to become confused about whether it is asleep or awake. When I open the lid, it seems to enter into sleep mode, but closing it seems to bring it into an active state.

Also, I've successfully logged on and authenticated with the screen showing exclusively on the external display. But just ten seconds after I start using the system, the laptop falls asleep--with the lid open! Whatever triggers that action doesn't seem to be on track. The laptop is open, there are incoming events such as mouse movements and key presses, and the external display is on and is in use. And then the laptop falls asleep! This has happened numerous times. Not only should this not happen; the instances where it does happen can cause further instability and put my system at risk of fatally crashing.

Also, the authentication system itself is highly buggy--far more than it should be. At times I have opened the laptop lid and caught a glimpse of a window before I have begun the login process. Also, an external authentication application that asks for Kerberos/AFS login credentials has been able to overlay itself on top of the primary authentication (whereas I should only see a single login dialog when I need to authenticate to the system). Also, I've had several of these authentication screens overlay on top of one another, although it's been months since I've experienced that one (so it may have been fixed). Also, around a third of the time, the window that authenticates me (on the black background) somehow transfers itself into the background (even though there's only one window!). What that means is what I begin to type my password, and now the laptop starts beeping at me and I need to manually click on the password field and begin entering my password again. This really shouldn't happen, and indicates too much complexity in this authentication process (such as, more OS X code is involved than is strictly necessary, which is likely to make the authentication system more difficult to test). Also, at times, I have been using too much CPU, such that the authentication screen takes too long to emerge. That also means that I'm not able to logon until I uncleanly shutdown the laptop. If the laptop has been asleep, and is revived in preparation for login, then that login screen should be given highest priority, even if there are other heavy CPU or I/O intensive tasks running in the background. And maybe the login dialog shouldn't disappear when the user is legitimately attempting to log in. So even if there is a possibility that the system is under heavy resource use (or there is a stall or minor deadlock), it shouldn't prevent the user from logging in altogether.

At the moment, the very fact that the system shut down uncleanly means that the full disk encryption suite that I used has entered into an undetermined state, suggesting I may lose access to all my data. It's my hope that I can rely on Apple's products to interoperate in a way that won't cause me to be fearful and restrictive in my use, so that I can freely connect an external display at times, and at other times carry the laptop on the road.

MacBook Pro, Mac OS X (10.5.8)

Posted on Apr 25, 2010 10:48 AM

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Ongoing fatal crash and security bug related to connecting external display

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