how to enable am335x Monitor debug-mode

Hi ,

The monitor debug mode can be configured in DSCR, which is writable via APB interface for am335x. But,  I read the DRAR(MRC p14, 0, <Rd>, c1, c0, 0) and DSAR(MRC p14, 0, <Rd>, c2, c0, 0). Both of them are invalid value (both are 0).

My question is how to enable am335x Monitor debug-mode?  Thanks a lot.

PS: I also ask the question at http://e2e.ti.com/support/arm/sitara_arm/f/791/p/334614/1167240.aspx#1167240

Thanks,

Pingchuan