the birdhouse in my soul

Found out the hard way: don't use underscores in hostnames. It's not allowed by DNS, and it breaks things. In this case: joining vCenter Server Appliance (VCSA) in an Active Directory doesn't work if the hostname of the appliance contains an underscore (_). It also doesn't work if the hostname is "localhost". If your appliance uses DHCP, the appliance gets its hostname through reverse DNS. So in that case, it _is_ a freaking DNS problem.

I won't blog about the whole vhv.allow="true" procedure here, that's been covered elsewhere. But what does nested virtualization change in a VM ? Well, the CPU features that are exposed change: A regular 64-bit Linux VM sees # grep flags /proc/cpuinfo flags : fpu vme de pse tsc msr pae mce cx8 apic mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss syscall nx rdtscp lm constant_tsc up arch_perfmon pebs bts rep_good xtopology tsc_reliable nonstop_tsc aperfmperf unfair_spinlock pni pclmulqdq ssse3 cx16 sse4_1 sse4_2 popcnt aes xsave avx hypervisor lahf_lm ida arat A 64-bit VM with nested virtualization enabled sees # grep flags /proc/cpuinfo flags : fpu vme de pse tsc msr pae mce cx8 apic mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss syscall nx rdtscp lm constant_tsc up arch_perfmon pebs bts rep_good xtopology tsc_reliable nonstop_tsc aperfmperf unfair_spinlock pni pclmulqdq vmx ssse3 cx16 sse4_1 sse4_2 popcnt aes xsave avx hy...