Re: [PATCH v2 3/3] target/m68k: add M68K_FEATURE_UNALIGNED_DATA feature

[Richard Henderson]

On 3/8/21 4:11 AM, Mark Cave-Ayland wrote:
> According to the M68040UM Appendix D the requirement for data accesses to be
> word aligned is only for the 68000, 68008 and 68010 CPUs. Later CPUs from the
> 68020 onwards will allow unaligned data accesses but at the cost of being less
> efficient.
>
> Add a new M68K_FEATURE_UNALIGNED_DATA feature to specify that data accesses are
> not required to be word aligned, and don't perform the alignment on the stack
> pointer when taking an exception if this feature is not selected.
>
> This is required because the MacOS DAFB driver attempts to call an A-trap
> with a byte-aligned stack pointer during initialisation and without this the
> stack pointer is off by one when the A-trap returns.
>
> Signed-off-by: Mark Cave-Ayland<mark.cave-ayland@ilande.co.uk>
> Reviewed-by: Laurent Vivier<laurent@vivier.eu>
> ---

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

r~