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Subject: Re: [Qemu-devel] [PATCH 6/7] monitor: "i": Add ARM specifics
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To: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Cc: Peter Maydell <peter.maydell@linaro.org>, "claudio.fontana" <claudio.fontana@gmail.com>, Peter Crosthwaite <crosthwaite.peter@gmail.com>, Alexander Graf <agraf@suse.de>, QEMU Developers <qemu-devel@nongnu.org>, Peter Crosthwaite <crosthwaitepeter@gmail.com>, "Edgar E. Iglesias" <edgar.iglesias@gmail.com>, Paolo Bonzini <pbonzini@redhat.com>

On 05/06/2015 12:06 AM, Peter Crosthwaite wrote:
> Can
> we rely on the env/CPUState always being up to date during
> target_disas (which happens at translate time?) or will we need to go
> field by field to make sure any env updates explicitly occur before
> target_disas?

I *think* so, but it's a near thing.  The path goes

 tb_find_fast:
  cpu_get_tb_cpu_state, fill fill in flags for TB from current ENV state.
  tb_find_slow,
    tb_gen_code, using those same flags.

There's the edge case of re-translation, but I'm going to assert that cpu mode
changes ought not happen in that context.  Doing otherwise means that the
kernel has just switched modes, the translator has failed to end the TB, and
the new code has faulted immediately.

What I don't know is if we can, at the moment, canonicalize on TB flags.  If
the monitor were to use cpu_get_tb_cpu_state, I know it would work when using
TCG, but I don't know if we keep all the same data up-to-date in KVM or XEN modes.


r~