how does x86_DEBUG_STATE64 work

Hi, I tried to create a thread today and when I switched to x86_DEBUG_STATE64 it crashed immediately. (I was also using x86_DEBUG_STATE64_COUNT). I had been using x86_THREAD_STATE64. I couldn't find any documentation on how these 'flavors' work or how they affect threads. How do I use x86_DEBUG_STATE64 and what does it buy me? Thanks btw I'm a new apple developer and using Yosemite. _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.... This email sent to site_archiver@lists.apple.com