How to enter USR mode from SVC mode?
Posted 01 August 2011 - 07:35 AM
OR anybody has some code some hwo to enter USR mode from SVC mode?
Posted 02 August 2011 - 03:01 AM
Here is how I do for Cortex-R4F :
mrs r1, cpsr
orr r1, r1, #0x0010
bic r1, r1, #0x000F
msr cpsr_c, r1
Hope it helps
I tried the code on Cortex-a8(freescale i.mx51), it does not work. Once "msr cpsr_c, r1" , a undefined instruction exception occured.
Posted 02 August 2011 - 06:53 AM
Hum, it is strange, because Cortex-A8 and R4 seem to share the same architecture !? What is your compiler ? (for me, it works with both RVCT 4.0 and CCS v4)
did you also try
msr cpsr, r1
cpsr_c is a sub mask for writing only specific bits... maybe not available for cortex-A8
This post has been edited by Christophe31: 02 August 2011 - 09:13 AM