Metalink Note 743042.1 has the Requirements for Installing Oracle 11gR1 RDBMS on Solaris 10 SPARC 64-bit.
The notable among these is kernel patch 137111-04.
There is a post on Sun blogs which describes Solaris 10 kernel patch id sequence. If you follow the obsolescence path of this patch, the curret patch which is not yet obsolete is 137137-09. So you should apply 137137-09 or higher to your Solaris 10 OS, before you can consider moving to 11g.
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