ESX Server 2.5.5: The Command /proc/version Shows Linux OS Redhat 7.1 (for ESX Server mode) and 7.2 (for UP and SMP mode).
Details
Reported kernel versions in /proc/version are inconsistent between booting in ESX Server mode and UP/SMP boot mode.
Solution
This is not a problem. The version base for the ESX Server vmnix kernel is different than the version base for the linux UP/SMP mode Linux kernels, and this is reflected in the output of the /proc/version node depending upon which kernel is booted. The ESX Server vmnix kernel is built from RedHat kernel source with modifications made by VMware. The two Linux kernels are binaries from RedHat security update kernel RPMs. Although relevant changes have been ported to the ESX Server kernel source, the base version has not changed.