See if you have good base in the subject of KANNADA then you can obviously go for it as an optional subject. Always know that in order to save time its better to choose subjects which you have interest at as well as which you are skilled in. Thus if you feel you have enough skills in Kannada just go for it. This will increase you chance of selection.

Also as you are choosing it as a literature subject then I would say you should try to conquer good vocabulary and grammar. Its very crucial for UPSC that you should be able to express your notion fluently through your writing by using appropriate words and phrases so that they don't get bulky. So keep this in mind.

Some of the books preferred by UPSC ASPIRANTS are:

• Bettada Jeeva - Shivarama Karanth.
• Madhavi- Arupama Niranjana.
• Odalaala - Devanuru Mahadeva.
• Janapada SWaroopa - Dr. H. M. Nayak.
• Janapriya Kanakasamputa - D. G. Javare Gowda.
• Kannada Janapada Kathegalu _ J. S. Paramashivaiah.
• Kannada Sanna Kathegalu - G. H. Nayak.

Etc.

Here the books for Optional Paper 1 -

• Linguistic History of Kannada Language - M. H. Krishnaiah.
• Kannada Bhasha Shastra - R. Y. Dharwadkar.
• Kannada Sahitya Chritre - R. S. Mugali.

To know more about UPSC visit the link below:

https://competition.careers360.com/articles/upsc-ias-syllabus

I hope this answer helps.