Re: [Qemu-devel] [PATCH] target-arm: Added CP15 VBAR support

[Peter Maydell]

On 27 February 2013 07:16, Peter Crosthwaite
<address@hidden> wrote:
> From: Nathan Rossi <address@hidden>
>
> Added Vector Base Address remapping on ARM v7.

This one's tricky because the VBAR only exists in CPUs with
TrustZone, and strictly speaking QEMU models a non-TrustZone
core. However we already have some dummy cp15 registers which
are really TZ-only just to get guests working, and this may
well fall into that category.

I need to have a think about how we can coherently define
what QEMU does about TZ so we can have a better idea of
what should and shouldn't be implemented. (If you have any
suggestions I'm open to them.)

On the patch itself:
 * you've forgotten to bump the cpu vmstate version
 * I'm trying to move towards using the official register
   abbreviations in cpu struct member names
 * the low bits of VBAR are "UNK/SBZP", which means our
   implementation must ignore writes and read as zeroes. So
   you need to do the masking in the write-accessor, not at
   point of use
 * we can just rely on the fact that the vbar field will be
   zero when QEMU is emulating a pre-v7 core, so you can
   avoid the feature check on use

thanks
-- PMM