Re: [Qemu-devel] [PATCH v2 1/3] boards.h: Define new flag ignore_memory_transaction_failures

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

On 09/05/2017 08:53 AM, Peter Maydell wrote:
> Define a new MachineClass field ignore_memory_transaction_failures.
> If this is flag is true then the CPU will ignore memory transaction
> failures which should cause the CPU to take an exception due to an
> access to an unassigned physical address; the transaction will
> instead return zero (for a read) or be ignored (for a write).  This
> should be set only by legacy board models which rely on the old
> RAZ/WI behaviour for handling devices that QEMU does not yet model.
> New board models should instead use "unimplemented-device" for all
> memory ranges where the guest will attempt to probe for a device that
> QEMU doesn't implement and a stub device is required.
> 
> We need this for ARM boards, where we're about to implement support for
> generating external aborts on memory transaction failures. Too many
> of our legacy board models rely on the RAZ/WI behaviour and we
> would break currently working guests when their "probe for device"
> code provoked an external abort rather than a RAZ.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>  include/hw/boards.h | 11 +++++++++++
>  include/qom/cpu.h   |  7 ++++++-
>  qom/cpu.c           | 16 ++++++++++++++++
>  3 files changed, 33 insertions(+), 1 deletion(-)

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


r~