[U-Boot] [RFC 1/1] efi_loader: refactor switch to hypervisor mode

[Mark Kettenis]

> From: Heinrich Schuchardt <xypron.glpk at gmx.de>
> Date: Wed, 26 Dec 2018 10:57:38 +0100
> 
> On 12/26/18 8:42 AM, Alexander Graf wrote:
> > 
> > On 26.12.18 03:02, Heinrich Schuchardt wrote:
> >>
> >> Thanks Mark for pointing this out.
> >>
> >> We have some major differences between bootm and bootefi:
> >>
> >> - Bootefi does not support CONFIG_ARMV8_SWITCH_TO_EL1 used by some
> >>   Xilinx boards.
> > 
> > Yeah, mostly because I really dislike boards that simply switch to EL1
> > for no good reason ;).

The only justification I can see for this is when EL2 is sufficiently
broken that it is inadvisable to have the kernel support
virtualization or if EL2 is used to work around broken hardware.  An
example of the latter is the Socionext Synqacer where virtualization
is used to fix up broken PCIe hardware.  Of course that U-Boot doesn't
use that SoC; the fixup happens in Tianocore.

> >> - It ignores CONFIG_ARMV8_PSCI.
> > 
> > What exactly should it honor here?
> 
> Call armv8_setup_psci() and possibly smp_kick_all_cpus().

Probably because most ARMv8 SoCs actually use TF-A to implement PSCI.