[U-Boot] Problem in accessing Contex ram

[Ronny D]

Hi,
 
I am using ppc440 based board.
While running the u-boot form DDR i am not able to access contex ram.
eg. 
  md 0xc0000000
 
u-boot generates machine check exception.
 
Here my doubt is can we access contex ram from u-boot running from DDR?
 
~Ronny