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I am going to build a secure system use arm trustzone technology. But it is said that the secure boot sequence is different between armv7 and armv8. I want to know what the difference is? And only secure boot is different or the boot sequence of armv7 and armv8 is different?

Any sort of help is appreciated.

roMoon
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    Well, the whole exception model is changed in v8 ([this might be a good place to start](http://infocenter.arm.com/help/topic/com.arm.doc.den0024a/CIHGCIDG.html)), but the difference is only visible in AArch64 state. There isn't really an architectural "boot sequence" beyond "come out of reset in the most privileged state (secure monitor/EL3)", but that was equally true of v7; can you clarify what exactly you're interested in here? – Notlikethat Jul 17 '15 at 08:01
  • thanks a lot @Notlikethat. What really confuse me is that if the change of EL affects the system boot sequence, such as bootrom->obm->uboot->os. As I am trying to port a secure os used for armv7 to armv8. – roMoon Jul 17 '15 at 08:22
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    The _system_ boot sequence depends entirely on details of a particular system - different chips might boot out of external NOR flash, internal flash, mask ROM, DRAM initialised by a system control processor, whatever; even across v7 systems there's huge variation. Everything beyond that (firmware, bootloader, OS, etc.) is pretty much your choice - you could go for something wildly different to u-boot (e.g. ARM Trusted Firmware and UEFI), or you could try and change as little as possible (see Exynos 5433 for the extreme of that). Depends on what you need vs. how much work you want to do. – Notlikethat Jul 17 '15 at 09:08
  • @Notlikethat, very helpful, thanks a lot. – roMoon Jul 17 '15 at 11:55

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