linux-kernel - Re: [PATCH 3/3] ARM: imx: add SMP support for i.MX7D

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Date:   Fri, 26 Aug 2016 10:59:11 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Anson Huang <Anson.Huang@....com>
Cc:     linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, shawnguo@...nel.org,
        kernel@...gutronix.de, fabio.estevam@....com, robh+dt@...nel.org,
        mark.rutland@....com, linux@...linux.org.uk
Subject: Re: [PATCH 3/3] ARM: imx: add SMP support for i.MX7D

On Friday, August 26, 2016 7:12:51 PM CEST Anson Huang wrote:
> i.MX7D has 2 cortex-a7 ARM core, add support for
> booting up SMP kernel with 2 CPUs.
> 
> The existing i.MX SMP code is designed for i.MX6
> series SoCs which have cortex-a9 ARM core, but i.MX7D
> has 2 cortex-a7 ARM core, so we need to add runtime
> check for those differences between cortex-a9 and
> cortex-a7.
> 
> Signed-off-by: Anson Huang <Anson.Huang@....com>
> 

Can't you just point i.MX7D to start from secondary_startup
rather than v7_secondary_startup?

 ENTRY(v7_secondary_startup)
+       .word   0xc070                  @ 0xc07 is cortex-a7 id
+       .word   0xfff0                  @ mask for core type
+

This looks like you are trying to execute instructions that are
actually data. Does this work?

On a side note, could you rename v7_secondary_startup to
imx6_secondary_startup? The name sounds overly generic
on a multiplatform kernel.

	Arnd