It is given in the caret documentation that to allow parallel processing the following code works
library(doMC) registerDoMC(cores = 5) ## All subsequent mode
Usually I do it like this adding allowParallel= TRUE :
allowParallel= TRUE
svmopt.caret=train(Y~.,data=nearsep1,method="svmLinear", trControl=trainControl(method="cv",number=10,search="grid"), tuneGrid=paramgrid, allowParallel=TRUE)