Execution stops while enabling MMU

[Björn König]

Hello,

I try to use FreeBSD with an AT91RM9200-based board similar to KB920X. I
use an existing boot loader (U-Boot running at 0x00000000) to copy the raw
binary kernel (not ELF) to the beginning of the SDRAM (0x20000000) and
execute it with the "go" command. But suddenly the execution stops while
enabling the MMU in src/sys/arm/arm/locore.S:

  /* Enable MMU */
  mrc     p15, 0, r0, c1, c0, 0
  orr     r0, r0, #CPU_CONTROL_MMU_ENABLE
  mcr     p15, 0, r0, c1, c0, 0

Code behind these lines won't be executed anymore. Here are some variables
that I use:

KERNPHYSADDR=0x20000000
KERNVIRTADDR=0xc0000000
PHYSADDR=0x20000000
STARTUP_PAGETABLE_ADDR=0x20800000

Does anybody have a hint for me? My knowledge about ARM architecture is
still superficially (literature already ordered ;-).

Regards
Björn