I think, we should be more clear about the caste system.
Yes, caste system has its orgins in Karma theory, which beleives that according to one's karma he is born into a caste. A person who has accumulated bad karma in his previous birth is born into lower castes or into animal species, whereas the one who accumulated good karma is born into higher castes. In fact, it is based on the birth only from the beginning.
But anyway such evil things are there in every religion in diferent forms. But once it is realised it is evil, we need to change.
Manu Smriti came into existence before Gita. So Manu Smriti does not mention about Gita. Gita does not say that caste is not based on birth. But nevertheless there is certain amount of flexibility in Gita. Gita says although caste is based on birth, the person's role becomes perfect of his caste only when he follows the rules laid for his caste. Anyway compared to Manu Smriti, Gita offers some positive definitions with respect to caste, like:
1. A wise man treats a Brahmin, an elephant or a Pariah with equal eye.
2. Irrespective of his caste he who comes to God will reach heaven.
3. Caste is limited only to body. The soul is pure and equal, whether he is Brahmin or the other.
According to Gita, caste restrictions must be followed, but that should not go beyond the limits to illtreat others.
Whereas Manu Smriti is purely restritive, authoritarian and controlling in its nature.
Anyway, irrespective of what religion said, now we realise that this caste system should be totally but systemmatically dismantled for the welfare of the nation and society.
Most important thing is there is need to raise the cultural, confidence and thinking levels of the weaker sections. They should be trained how to compete and how to improve their motivation level. They should given some out of the curriculum training, which should include communications skills, English language skills, personality development, etc.
Simply distributing quotas for different castes does not bring any permanent change. These disparities will continue further prolonging the reservation system. People who are very weak need reservations. But that should not be a pre-planned permanent thing.
Caste system is an evil. To undo that evil reservations were created. But, today, thanks to our politicians, we are living with two evils--caste system and reservation system.
We need more scientific and systemmatic approach to reform the caste system.
PS: The above are personal opinions. Some of the above written things may need improvements or corrections.