On a Solaris 10 X86 server, based purely on the showrev -poutput; is it at all possible to identify the date of the 10_x86_Recommended_CPU patch cluster used to update the machine?
Which packages, in addition to the kernel patch level, would you consider important to check?
Solaris release engineering does not work that way. There is nothing in Solaris 10 (and earlier) patches to identify the date, and this is on purpose. If you are able to regularly patch your system(s), then apply the recommended patch cluster, which one can download if one has an Oracle Technology Network login (gratis) which is tied to a valid support contract (non gratis).
Solaris release can be determined by looking at /etc/release. The uN, for example "u10" is the number of the updates since the general availability ("GA") release, so for example Solaris 10 u10 means that the operating system is the 10th generation of Solaris 10. However, this string is not necessarily (or at all) updated when applying a recommended patch cluster, and may not be relied upon by any code, as it is a freeform string and not a committed interface or specification. The only way to know for sure is to run
showrev -p
The patch naming format in Solaris 10 and prior releases is simple: seven digit part number, followed by a two digit revision.
In solaris the patch are numerated, showrev -p shows all installed patched and cluster patchs too, if you are looking for a patch you need:
showrev -p | grep <path_number>
