On 29 December 2013 19:10, TigerLiu@viatech.com.cn wrote:
Hi, Dall: I have a few questions about switching cpu's state from secure to non-sec in uboot.
- I found do_nonsec_virt_switch() function had been integrated in
uboot_2014_01_RC2. This function would switch cpu from secure state to non-sec, even into hyp-state. So, my question is: If a SOC is based on ARMv7 architecture: Virt-v7.c / nonsec_virt.S are common files to all kinds of SOCs which are produced by different Vendors?
Yes, the aim is to be able to reuse as much of this code for as many platforms as possible.
- Does uboot need to switch its state to non-sec? Based on ARM company released doc: U-boot should run at non-sec state, so no need to swith to non-sec
again.
It depends on the board. Which ARM doc are you referring to?
In general, there are three options for how u-boot is booted: 1. In secure mode 2. In non-secure hyp mode 3. in non-secure svc mode
for (1) you can just switch to non-secure hyp. for (2) you don't have to do anything. for (3) you're screwed, unless there's a backdoor call to enter Hyp mode (typically found on TI hardware).
If we are talking PSCI, that's a different story, and if that's provided by the board and not U-boot (see Marc's recent work), then I would expect that board to always boot U-boot in Hyp mode to be coherent with the documentation.
-Christoffer