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I have a samsung exynos 4412(Cortex-A9) development board. There is a simple secure os that can run on it. The normal os is Android. Now I am trying to select linux as the secure os. The linux kernel is from the Android OS for the development board. The kernel version is 3.0.15. It can run pretty well when it is in normal world. When I switch to the secure world(clear the NS bit), the kernel will stop at the calibrate_delay() function in init/main.c. That is to say, the kernel uncompressed code is executed correctly and the first C function of the kernel, start_kernel(), is also executed. Almost all the initialization functions run well except running to calibrate_delay(). This function will wait for the jiffies changed:
/* wait for "start of" clock tick */
ticks = jiffies;
while (ticks == jiffies);
I guess the reason is no clock interrupt is raised(I print logs in clock interrupt callback functions, they are never gotten in). I have checked the CPSR state before and after the local_irq_enable() function. The IRQ and FIQ bit are set correctly. I also print some logs in the Linux kernel's IRQ handler defined in the interrupt vectors table. Nothing logged.
I am definitely a newbie in linux kernel and trustzone. Can anybody tell me what the problem is? Or more important thing is can a linux kernel run as the trustzone secure os? Are there any reference manual to do this? Thank you.
Yes TZC provides you mechanism to control and clearly partition the access to various
memory regions(not just DRAM, anything memory mapped including all IOs) between
the secure and non-secure world.