Re: [Qemu-devel] [PATCH 1/7] target/arm: Add armv7m_nvic_set_pending_derived()

[Richard Henderson <richard.henderson@linaro.org>]

On 01/30/2018 07:02 AM, Peter Maydell wrote:
> In order to support derived exceptions (exceptions generated in
> the course of trying to take an exception), we need to be able
> to handle prioritizing whether to take the original exception
> or the derived exception.
> 
> We do this by introducing a new function
> armv7m_nvic_set_pending_derived() which the exception-taking code in
> helper.c will call when a derived exception occurs.  Derived
> exceptions are dealt with mostly like normal pending exceptions, so
> we share the implementation with the armv7m_nvic_set_pending()
> function.
> 
> Note that the way we structure this is significantly different
> from the v8M Arm ARM pseudocode: that does all the prioritization
> logic in the DerivedLateArrival() function, whereas we choose to
> let the existing "identify highest priority exception" logic
> do the prioritization for us. The effect is the same, though.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>  target/arm/cpu.h      | 13 ++++++++++
>  hw/intc/armv7m_nvic.c | 68 +++++++++++++++++++++++++++++++++++++++++++++++++--
>  hw/intc/trace-events  |  2 +-
>  3 files changed, 80 insertions(+), 3 deletions(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>


r~