Re: [PATCH v2] target/s390x: improve cpu compatibility check error message

[Nina Schoetterl-Glausch <nsg@linux.ibm.com>]

On Thu, 2024-03-14 at 22:37 +0100, Claudio Fontana wrote:
> some users were confused by this message showing under TCG:
> 
> Selected CPU generation is too new. Maximum supported model
> in the configuration: 'xyz'
> 
> Clarify that the maximum can depend on the accel, and add a
> hint to try a different one.
> 
> Also add a hint for features mismatch to suggest trying
> different accel, QEMU and kernel versions.
> 
> Signed-off-by: Claudio Fontana <cfontana@suse.de>

Reviewed-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>

> ---
>  target/s390x/cpu_models.c | 22 +++++++++++++++-------
>  1 file changed, 15 insertions(+), 7 deletions(-)
> 
> diff --git a/target/s390x/cpu_models.c b/target/s390x/cpu_models.c
> index 1a1c096122..8ed3bb6a27 100644
> --- a/target/s390x/cpu_models.c
> +++ b/target/s390x/cpu_models.c
> @@ -500,6 +500,16 @@ static void error_prepend_missing_feat(const char *name, void *opaque)
>      error_prepend((Error **) opaque, "%s ", name);
>  }
>  
> +static void check_compat_model_failed(Error **errp,
> +                                      const S390CPUModel *max_model,
> +                                      const char *msg)
> +{
> +    error_setg(errp, "%s. Maximum supported model in the current configuration: \'%s\'",
> +               msg, max_model->def->name);
> +    error_append_hint(errp, "Consider a different accelerator, try \"-accel help\"\n");
> +    return;
> +}
> +
>  static void check_compatibility(const S390CPUModel *max_model,
>                                  const S390CPUModel *model, Error **errp)
>  {
> @@ -507,15 +517,11 @@ static void check_compatibility(const S390CPUModel *max_model,
>      S390FeatBitmap missing;
>  
>      if (model->def->gen > max_model->def->gen) {
> -        error_setg(errp, "Selected CPU generation is too new. Maximum "
> -                   "supported model in the configuration: \'%s\'",
> -                   max_model->def->name);
> +        check_compat_model_failed(errp, max_model, "Selected CPU generation is too new");
>          return;
>      } else if (model->def->gen == max_model->def->gen &&
>                 model->def->ec_ga > max_model->def->ec_ga) {
> -        error_setg(errp, "Selected CPU GA level is too new. Maximum "
> -                   "supported model in the configuration: \'%s\'",
> -                   max_model->def->name);
> +        check_compat_model_failed(errp, max_model, "Selected CPU GA level is too new");
>          return;
>      }
>  
> @@ -537,7 +543,9 @@ static void check_compatibility(const S390CPUModel *max_model,
>      error_setg(errp, " ");
>      s390_feat_bitmap_to_ascii(missing, errp, error_prepend_missing_feat);
>      error_prepend(errp, "Some features requested in the CPU model are not "
> -                  "available in the configuration: ");
> +                  "available in the current configuration: ");
> +    error_append_hint(errp,
> +                      "Consider a different accelerator, QEMU, or kernel version\n");

If I'm reading the regex right, this ^, a string literal on a separate line, is excluded
from the line length check.

>  }
>  
>  S390CPUModel *get_max_cpu_model(Error **errp)