Do I need ATF source code if I want to port to a new SoC (like RK33xx)?

[cnnblike]

The manufacture don't provide ATF source code for my target SoC, is it still plausible to port bao-hypervisor?

[josecm]

Hello @cnnblike . Yes of course. If they dont provide source code, I would guess that at least they provide some binary or the firmware is already there. For running Bao ATFA needs to be there, but you don't need to compile it or have control over it.

[cnnblike]

hey, thanks for the reply.
I was reading into the boot chain of bao hypervisor, and got confused by the make.mk under bao-demo linux+freertos part. It looks like we are trying to build dts with linux together with the linux kernel image.
I was wondering, like, shouldn't the normal process be 1. bootloader (normally be uboot) load the dtb to memory 2. put some magic number in register r0,r2 3. kernel identify the taglist and then pick the dtb up?
Why do we need a specific kernel image bundled with dtb?
Normally the chain would be kinda like atf - - uboot - linux, then why do we need a specific image with dtb for bao? Whats the correct boot sequence? atf-bao-uboot-kernel or atf-uboot-bao-kernel?

[josecm]

It looks like we are trying to build dts with linux together with the linux kernel image.

Yes we are.

I was wondering, like, shouldn't the normal process be 1. bootloader (normally be uboot) load the dtb to memory 2. put some magic number in register r0,r2 3. kernel identify the taglist and then pick the dtb up?
Why do we need a specific kernel image bundled with dtb?

You could actually put a u-boot inside the virtual machine and give u-boot the "trimmed" device tree according to that VM configruation. We just skip that step because is not completely needed (being a virtual machine). We bundle the kernel image with a dtb and a small stub that initializes the registers as you mention. The onluy reason we do it like this: its simpler and quicker.

Normally the chain would be kinda like atf - - uboot - linux, then why do we need a specific image with dtb for bao? Whats the correct boot sequence? atf-bao-uboot-kernel or atf-uboot-bao-kernel?

Indeed we need a specific device tree for linux guests running over bao that matches we the configuration of the VM its running on. Otherwise linux will try to accesss resources described in the device tree that are not assigned to it by bao.

The boot flow yes is atf-uboot-bao- VM. Inside the vm you can put whatever you run as long it is targetted at EL1/0 privilege levels, including u-boot. But if you want to run linux you are not required to have u-boot the only thing you need is the image and the device tree describing the VM resources (as I said, this is simpler).