(an update of an older post, now complete up to vSphere 6) Your Linux runs on a VMware VM, but which on which ESXi version? You can see for yourself: run "dmidecode" and look at lines 10, 11 and 12. ESX 2.5 - BIOS Release Date: 04/21/2004 - Address 0xE8480 - Size 97152 bytes ESX 3.0 - BIOS Release Date: 04/17/2006 - Address 0xE7C70 - Size 99216 bytes ESX 3.5 - BIOS Release Date: 01/30/2008 - Address 0xE7910 - Size 100080 bytes ESX 4 - BIOS Release Date: 08/15/2008 - Address 0xEA6C0 - Size 88384 bytes ESX 4U1 - BIOS Release Date: 09/22/2009 - Address 0xEA550 - Size 88752 bytes ESX 4.1 - BIOS Release Date: 10/13/2009 - Address 0xEA2E0 - Size 89376 bytes ESXi 5 - BIOS Release Date: 01/07/2011 - Address 0xE72C0 - Size 101696 bytes ESXi 5.1 - BIOS Release Date: 06/22/2012 - Address: 0xEA0C0 - Size: 89920 bytes ESXi 5.5 - BIOS Release Date: 07/30/2013 - Address: 0xEA050 - Size: 90032 bytes ESXi 6 - BIOS Release Date: 09/30/2014 - Address: 0xE9A40 - Size: 91584 bytes N
plenty of grains to pick