[PATCH 61/62] ARM: sunxi: fix build for THUMB2_KERNEL

Maxime Ripard
2014-03-21T19:11:27Z

On Fri, Mar 21, 2014 at 10:54:49AM -0500, Rob Herring wrote:
> >
> > .arm
> > ENTRY(sun6i_secondary_startup)
> > ARM_BE8(setend be ) /* I suppose we need this too */
> > msr cpsr_fsxc, #0xd3
> > ldr r0, =secondary_startup
> > bx r0
> >
> > (I'm a bit confused about when to use what branch instruction, so
> > forgive me if the above doesn't make sense)
> >
> >> Also, secondary_startup takes care of making sure the core is in SVC
> >> mode, so this function shouldn't be needed in the first place.
> >
> > I'd rather not change this part, unless Maxime can confirm that it's
> > not necessary. I would assume that it's there for a reason otherwise.
>
> That often proves to not be the case. :) Initial SOC code is whatever
> we've failed to delete from vendor BSP code.

Yep, it definitely looks like it.

> Looking at the review comments adding SMP boot, there was discussion
> about entering in HYP mode and that being dependent on u-boot support,
> but nothing whether this was needed or not. So it appears to me we
> probably enter the kernel in the reset default of secure supervisor
> mode and this code is a nop. This code would not work if it was HYP
> mode. So when u-boot does correctly setup HYP mode, this code will be
> broken (although other parts of smp_ops will be too).

Actually, we don't have any proper bootloader support for this SoC,
and we're stuck with Allwinner's bootloader.

Bootloader support will come eventually, but I wouldn't worry too much
about HYP for now. And whenever we will have such a bootloader, we
will use PSCI, so we won't need to worry about it either.

--
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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