PROCESSOR-SDK-OMAPL138: Can't access the ISTP register in the boot program

Part Number:PROCESSOR-SDK-OMAPL138

Dear TI team,

I am developing a device using OMAPL138 processor.
I want to access to the ISTP register to set the interrupt vector table pointer.
I read and followed the "Example 6-1 Relocation of Interrupt Service Table" in "Section 6.1.1.6 Interrupt Service Table Pointer (ISTP)". Document SPRUGH7 November 2010.
When I run this example in the program in debug mode, I can access normally the ISTP register. But when executing programs by booting from NAND, access to this register is not possible. The program is hung. I have checked the TSR.CMX before accessing the ISTP and found it to be 00 (supervisor mode).

The program runs on C674x DSP and the address I wrote to ISTP is 0x00800000.

Could you please help me to resolve this issue?

Thanks,

Truong