while I’m trying to generating rtosdemo-a.bin file it’s showing following error: /../source/portable/GCC/AM 335_BeagleBone/PortISR.c:1:0 error:bad value(cortex-a8) for -mtune=switch so anyone can help how to handle this error??

This is just a compiler syntax problem, not a FreeRTOS problem by the look of it. The -mtune option should be followed by the name of a cpu, so “switch” does not look valid. The GCC manual or searching “GCC command line options mtune” should give you a list of valid cpu times. I think there is even a command line option to get GCC to print out a list of valid values for its configuration but I can’t remember what it is without looking it up myself.