Check if VT-X is enabled and improve related documentation

[thaJeztah]

Docker Toolbox (VirtualBox) fails to run if VT-X isn't supported or not enabled on the hardware it runs on. This is a placeholder issue for improving the checks, feedback and instructions to handle hardware that doesn't have VT-X (enabled).

Docker Toolbox should;

• Check if VT-X is enabled (for OS X, this article http://kb.parallels.com/en/5653 explains checking via sysctl -a | grep machdep.cpu.features)
• (better) Document that VT-X should be supported and enabled
• Add instructions / documentation how to check if VT-X is enabled and/or enable it (for OS X; https://support.apple.com/en-us/HT203296)

Given that there's an overlap between "Docker Machine", "Docker Toolbox", and "Boot2Docker", documenting it in the right places could be a challenge (users are reporting these issues in all repos 😄)

VT-X related issues are already mentioned in #65, #119, and reported in the docker repository; moby/moby#11877, moby/moby#15712, moby/moby#15982

[mchiang0610]

@thaJeztah Thanks for submitting this. This is something we definitely need.

[thaJeztah]

@mchiang0610 this could be useful information as well; moby/moby#16182 (comment)

[mchiang0610]

@thaJeztah Thanks. New Macs have VT-X enabled by default. We haven't seen any problems there.

Many Windows users on the other hand have experienced this issue. Some workstations like Microsoft's Surface Pro 3 has VT-X enabled by default.

I have added a readme change to help users. See PR here: #170

[thaJeztah]

You may be right on the OS X part, I think all that's needed is to have the firmware up to date (I see moby/moby#11877 (comment) is running OS X on Hackintosh).

Still, if the installer would be able to detect it, that'd be nice :-)

[mchiang0610]

@thaJeztah Agreed! That will come. It's just that at the moment we are focused on bug fixes to cut down failure rates. :)

[thaJeztah]

👍 sgtm