Re: [U-Boot] [PATCH v4 04/14] ARM: Factor out reusable psci_cpu_entry

On Sat, 2015-02-28 at 13:53 +0000, Marc Zyngier wrote:

...

+ENTRY(psci_cpu_entry)

• @ Set SMP bit
• mrc p15, 0, r0, c1, c0, 1 @ ACTLR
• orr r0, r0, #(1 << 6) @ Set SMP bit
• mcr p15, 0, r0, c1, c0, 1 @ ACTLR
• isb
• bl _nonsec_init
• adr r0, _psci_target_pc
• ldr r0, [r0]
• b _do_nonsec_entry

+ENDPROC(psci_cpu_entry)

I'd add a *big* comment at the top of this. ACTLR is implementation dependent, and while sticking the SMP bit at this location is fairly common among ARM cores, it is by no mean a strong guarantee (this is not an architectural feature).

I'd recommend making it override-able.

Tom R has a series which does something along those lines: https://patchwork.ozlabs.org/patch/431587/

I suppose it ought to be used here too one way or another.

Ian.