On 04.10.2017 17:41, Halil Pasic wrote:
> CSS code needs to tell the IO instruction handlers located in how should
located in how?
> the emulated instruction be ended. Currently this is done by returning
> generic (POSIX) error codes, and mapping them to outcomes like condition
> codes. This makes bugs easy to create and hard to recognise.
>
> As a preparation for moving a way form (mis)using generic error codes for
> flow control let us introduce a struct which tells the instruction
> handler function how to end the instruction, in a more straight-forward
> and less ambiguous way.
>
> Signed-off-by: Halil Pasic <pa...@linux.vnet.ibm.com>
> ---
> include/hw/s390x/css.h | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/include/hw/s390x/css.h b/include/hw/s390x/css.h
> index 0653d3c9be..66916b6546 100644
> --- a/include/hw/s390x/css.h
> +++ b/include/hw/s390x/css.h
> @@ -75,6 +75,18 @@ typedef struct CMBE {
> uint32_t reserved[7];
> } QEMU_PACKED CMBE;
>
> +/* IO instructions conclude according this */
> +typedef struct IOInstEnding {
> + /*
> + * General semantic of cc codes of IO instructions is (brief):
> + * 0 -- produced expected result
> + * 1 -- status conditions were present or produced alternate result
> + * 2 -- ineffective, because busy with previously initiated function
> + * 3 -- ineffective, not operational
> + */
> + int cc;
> +} IOInstEnding;
Why do you need a struct for this? Do you plan to extend it later? If
so, I think you should mention that in the patch description. If not,
please use a named enum or a "typedef unsigned int IOInstEnding" instead.
Thomas
