Re: [PATCH] ARM: EXYNOS: mcpm: Don't rely on firmware's secondary_cpu_start

From: Doug Anderson
Date: Fri Jun 13 2014 - 11:10:29 EST


Chander,

On Fri, Jun 13, 2014 at 4:54 AM, Chander Kashyap <k.chander@xxxxxxxxxxx> wrote:
> This patch is effectively changing the mcpm_entry_point address from
> nsbase + 0x1c to nsbase + 0x8
>
> Hence while integrating with mainline u-boot we need to take care for
> new mcpm_entry_point address.
>
> With Chromebook it works straightforward.

Can you explain more and point to the code that is using the nsbase +
0x1c? Specifically the only code I see that uses the nsbase + 0x1c is
the code that is located at nsbase, which is the code we're
overwriting here. I'd imagine you're using U-Boot code that looks
something like the bits that start at code_base here:

https://chromium.googlesource.com/chromiumos/third_party/u-boot/+/ce358daf5069f1dc145b0f9d403cfbb028271807/arch/arm/cpu/armv7/exynos/lowlevel.S

With my kernel change you can completely eliminate U-Boot's
installation of this code (or keep it, it makes no difference).

-Doug
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