[PATCH 1/3] arm64: merge __enable_mmu and __turn_mmu_on

Mark Rutland mark.rutland at arm.com
Wed Mar 18 05:09:24 PDT 2015

> >> - * Setup common bits before finally enabling the MMU. Essentially this is just
> >> - * loading the page table pointer and vector base registers.
> >> + * Enable the MMU. This completely changes the structure of the visible memory
> >> + * space. You will not be able to trace execution through this.
> >
> > I don't understand the last sentence. I recall being able to read and
> > eventually understand simulator instruction traces of this code. Is the
> > sentence referring to the Embedded Trace Macrocell or something?
> >
> I guess the comment is a bit stale: it was inherited from the ARM
> version, where older platforms only have a single TTBR register, and
> switching address spaces is a bit more involved. On arm64, however,
> there are always two TTBR registers at EL1, and the address spaced
> they represent can never overlap, so there it isn't such a big deal.

Indeed. Feel free to drop it if you want.


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