On Tue, Apr 23, 2019 at 02:17:23PM +0000, Benjamin GAIGNARD wrote: > On 4/23/19 3:55 PM, Sudeep Holla wrote:
> > The above statement makes me wonder if Cortex-M4 firmware is really > > non-secure, if so why does it need such an isolation from other masters > > like Cortex-A7. For me Cortex-M4 is secure and Cortex-A7 can execute > > in non-secure hence Cortex-M4 needs to be isolated from Cortex-A7 as > > mentioned in the above excerpts from the datasheet. > Cortex-M4 firmware is non-secure, it could be a free RTOS. > ETZPC doesn't isolate Cortex M4 or A7 but control which of them have > access to hardware blocks. > For example ETZPC controls if M4 or A7 can have access to I2C hardware > blocks. The goal is to make sure > firmware running on each side don't use the hardware blocks of the other > side. The goal AIUI is mainly for robustness rather than security - trying to mitigate against any bugs that might happen, making them more apparent during development and mititgating their impact if they slip through.
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