[LITMUS^RT] trouble in userlibrary

[250680 RA1613004011003]

Hi friends,i have installed litmusrt files and patch files in ubuntu 14.04
.After booting the VM i tried to install with liblitmus files but i cant
make liblitmus files .

Error make 276: *** cannot  build without access to the litmusrt kernel
source.

how to resolve this?
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