[U-Boot] ARMv8 switching CPUs into EL1

[Michal Simek]

Hi,

On 06. 06. 19 15:15, Mels van Broekhoven wrote:
> L.S.!
> 
> On a Xilinx ZynqMP-based platform with u-boot running in Aarch64 mode in
> EL2, after booting a Linux kernel  in EL1 using CONFIG_ARMV8_SWITCH_TO_EL1,
> Linux throws a warning that the CPUs have started in inconsistent modes
> ("CPU: CPUs started in inconsistent modes").
> Indeed, only the first core on which U-boot was running is switched to EL1
> at this point.
> 
> Is this a bug or a not completely supported feature in U-boot or can this
> warning actually be safely ignored under certain circumstances?

I have take a look at the path and what it is happening is that ATF
records that cpu0 started in EL2. Then u-boot starts Linux in EL1
because of macro above. And then Linux is asking from EL1 ATF to turn on
CPU but ATF has a record that CPU0 started in EL2 that's why it starts
others cpus in EL2. And then Kernel reports back that it is not consistent.

Thanks,
Michal

-- 
Michal Simek, Ing. (M.Eng), OpenPGP -> KeyID: FE3D1F91
w: www.monstr.eu p: +42-0-721842854
Maintainer of Linux kernel - Xilinx Microblaze
Maintainer of Linux kernel - Xilinx Zynq ARM and ZynqMP ARM64 SoCs
U-Boot custodian - Xilinx Microblaze/Zynq/ZynqMP/Versal SoCs


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