Invalidatin Cortex-A9 SCU

[vsiles]

Hi !

I'm trying to understand how to enable ACTLR.SMP and the SCU on our own secure OS, and the Cortex-A9 TRM states that:

For the primary processor:
1. Invalidate:
   • the SCU duplicate tags for all processors
   • the data cache.
2. Enable the SCU.
3. Enable the data cache, set the SMP mode with ACTLR.SMP=1.

While reading Linux code, I found that the SCU is enabled quite late in the boot process (mmu is already on, and L1/L2 caches are already configured), and the only bit set at this time are ENABLE and STANDBY_ENABLE. I can't find any invalidation of the SCU tags.

1. Is not invalidating the SCU before enabling an issue ?
2. Why does Linux enables the SCU so late in the boot process ?

Best,

V.

[Yuri · Accepted solution]

Hello,

It is assumed, that the SCU after POR is invalidated.

Have a great day,

Yuri

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