ARM AT91SAM9260 - RT patched system not running

Hello rt-list!

I have compiled Kernel 2.6.33.7 with rt-patches and arm-patches
(http://maxim.org.za/AT91RM9200/2.6/2.6.33-at91.patch.gz) for an ARM AT91SAM9260. The system stops running at

Freeing init memory

I traced this down to the file linux-2.6.33.7/arch/arm/kernel/sys_arm.c , where an assembler command does not return. Check this code snippet:

printk("HELLO 1\n");
    asm(    "add    r0, %0, %1\n\t"
        "mov    r1, %2\n\t"
        "mov    r2, %3\n\t"
        "bl    memmove\n\t"    /* copy regs to top of stack */
        "mov    r8, #0\n\t"    /* not a syscall */
        "mov    r9, %0\n\t"    /* thread structure */
        "mov    sp, r0\n\t"    /* reposition stack pointer */
        "b    ret_to_user"
        :
        : "r" (current_thread_info()),
          "Ir" (THREAD_START_SP - sizeof(regs)),
          "r" (&regs),
          "Ir" (sizeof(regs))
        : "r0", "r1", "r2", "r3", "ip", "lr", "memory");

printk("HELLO 2\n");

"HELLO 1" can still be read, "HELLO 2" never appears.

Any idea, what could be the problem?

Kind regards,
Dennis