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

On Fri, Mar 21, 2014 at 10:54:49AM -0500, Rob Herring wrote:

quoted

.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)

quoted

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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