Hi,
On a 440gx platform I wrote a small stand alone app for debugging. I tried to
Hook the ISR at 0x700 and use a trap instruction.
I replaced the isr routine w/my own. In the process I discovered the isr at 0x700 does nothing except store the
Address of the service routine and return handler at addresses 0x788 and 0x78c.
I stubbed the entire routine
And it still works as long as the above addresses are there.
How does u-boot execute a trap instruction without
Executing at least a branch instruction from the trap location 0x700? IVPR and IVOR6 are set correctly.
How does it get to the global transfer_to_handler routine??
Thanks
Don Russell
+$#00-$DOK#demsg:#
in svc rtn
MSR=0x9000, srr0=0x7088
ivpr=0x0, ivor6=0x700
pc= 0x403C , ad=0x1FF4E498
msr 0x00029000
lr 0x00004034
cr 0x24022222
trap 0x00000700
addr=0x700, 0x4C00012C =isync
addr=0x704, 0x4C00012C
addr=0x708, 0x4C00012C
addr=0x70C, 0x4C00012C
addr=0x710, 0x4C00012C
addr=0x714, 0x4C00012C
addr=0x718, 0x4C00012C
addr=0x71C, 0x4C00012C
addr=0x720, 0x4C00012C
addr=0x724, 0x4C00012C
addr=0x728, 0x4C00012C
addr=0x72C, 0x4C00012C
addr=0x730, 0x4C00012C
addr=0x734, 0x4C00012C
addr=0x738, 0x4C00012C
addr=0x73C, 0x4C00012C
addr=0x740, 0x4C00012C
addr=0x744, 0x4C00012C
addr=0x748, 0x4C00012C
addr=0x74C, 0x4C00012C
addr=0x750, 0x4C00012C
addr=0x754, 0x4C00012C
addr=0x758, 0x4C00012C
addr=0x75C, 0x4C00012C
addr=0x760, 0x4C00012C
addr=0x764, 0x4C00012C
addr=0x768, 0x4C00012C
addr=0x76C, 0x4C00012C
addr=0x770, 0x4C00012C
addr=0x774, 0x4C00012C
addr=0x778, 0x4C00012C
addr=0x77C, 0x4C00012C
addr=0x780, 0x4C00012C
addr=0x784, 0x4C00012C
addr=0x788, 0x6B1C =trapservice
addr=0x78C, 0x7E60 =return handler
+$#00