SMP on RPI5

[preetamsad]

Hello @rsta2, I am porting RTEMS for RPI5, and Circle has been a great resource. So far, I have a basic BSP with the debug uart, generic timer and gic interrupt. Thanks to your memory map notes and your notes on debugging, its been a great help. I am also posting on a discourse thread about the bring up process, you can take a look for more context.

Now, I am at a point where I am trying to add SMP support for Pi5. I wanted to ask if you could help me in the right direction with this. I am not sure if this is suitable for github discussion or not, but I wanted to give it a go. If not, please let me know how I should contact you instead. Thanks.

I have looked at the BCM2712 device tree source, and it says the CPUs uses PSCI with SMC. I tried it but could not make it work, so I looked at the ATF/TF-A source and it seems the Pi5's PSCI impelmentation is not a standard implementation? It ignores the x2 register for the smc #0 call and instead relies on hardcoded ram address to pass the jump address. I wanted to confirm if this is true or not and how does Circle deals with it. After quick glance in Circle, it seems like it does actually use PSCI with SMC to do SMP but I am not sure how. It would be great if you can help me with this.

Also, if you could tell me anything to look for like any quirks in bringing up the PI5 on a new platform, I would appreciate it. Thanks!! 😀

[rsta2]

SMP support for RPi 5 is in lib/multicore.cpp. This should tell everything, you need. I'm not aware of any quirks.