CONFIG_ALTIVEC is not available for the default architecture x86.
Result is shown for architecture powerpc

AltiVec Support

modulename: vecemu.ko


configname: CONFIG_ALTIVEC

Linux Kernel Configuration
└─> Processor support
└─> AltiVec Support

This option enables kernel support for the Altivec extensions to the
PowerPC processor. The kernel currently supports saving and restoring
altivec registers, and turning on the 'altivec enable' bit so user
processes can execute altivec instructions.

This option is only usefully if you have a processor that supports
altivec (G4, otherwise known as 74xx series), but does not have
any affect on a non-altivec cpu (it does, however add code to the

If in doubt, say Y here.

source code: