Re: [RFC 3/3] qom: Improve error message in module_object_class_by_name()

[Claudio Fontana]

On 7/1/21 1:27 AM, Jose R. Ziviani wrote:
> module_object_class_by_name() calls module_load_qom_one if the object
> is provided by a dynamically linked library. Such library might not be
> available at this moment - for instance, it can be a package not yet
> installed. Thus, instead of assert error messages, this patch outputs
> more friendly messages.
> 
> Current error messages:
> $ ./qemu-system-x86_64 -machine q35 -accel tcg -kernel /boot/vmlinuz
> ...
> ERROR:../accel/accel-softmmu.c:82:accel_init_ops_interfaces: assertion 
> failed: (ops != NULL)
> Bail out! ERROR:../accel/accel-softmmu.c:82:accel_init_ops_interfaces: 
> assertion failed: (ops != NULL)
> [1]    31964 IOT instruction (core dumped)  ./qemu-system-x86_64 ...
> 
> New error message:
> $ ./qemu-system-x86_64 -machine q35 -accel tcg -kernel /boot/vmlinuz
> accel-tcg-x86_64 module is missing, install the package or config the library 
> path correctly.
> 
> $ make check
> ...
> Running test qtest-x86_64/test-filter-mirror
> Running test qtest-x86_64/endianness-test
> accel-qtest-x86_64 module is missing, install the package or config the 
> library path correctly.
> accel-qtest-x86_64 module is missing, install the package or config the 
> library path correctly.
> accel-qtest-x86_64 module is missing, install the package or config the 
> library path correctly.
> accel-qtest-x86_64 module is missing, install the package or config the 
> library path correctly.
> accel-qtest-x86_64 module is missing, install the package or config the 
> library path correctly.
> accel-tcg-x86_64 module is missing, install the package or config the library 
> path correctly.
> ...
> 
> Signed-off-by: Jose R. Ziviani <jziviani@suse.de>
> ---
>  qom/object.c | 30 ++++++++++++++++++++++++++++++
>  1 file changed, 30 insertions(+)
> 
> diff --git a/qom/object.c b/qom/object.c
> index 6a01d56546..2d40245af9 100644
> --- a/qom/object.c
> +++ b/qom/object.c
> @@ -1024,6 +1024,24 @@ ObjectClass *object_class_by_name(const char *typename)
>      return type->class;
>  }
>  
> +char *get_accel_module_name(const char *ac_name);
> +
> +char *get_accel_module_name(const char *ac_name)
> +{
> +    size_t len = strlen(ac_name);
> +    char *module_name = NULL;
> +
> +    if (strncmp(ac_name, "tcg-accel-ops", len) == 0) {
> +#ifdef CONFIG_TCG_MODULAR
> +        module_name = g_strdup_printf("%s%s", "accel-tcg-", "x86_64");
> +#endif
> +    } else if (strncmp(ac_name, "qtest-accel-ops", len) == 0) {
> +        module_name = g_strdup_printf("%s%s", "accel-qtest-", "x86_64");
> +    }
> +
> +    return module_name;
> +}
> +
>  ObjectClass *module_object_class_by_name(const char *typename)
>  {
>      ObjectClass *oc;
> @@ -1031,8 +1049,20 @@ ObjectClass *module_object_class_by_name(const char 
> *typename)
>      oc = object_class_by_name(typename);
>  #ifdef CONFIG_MODULES
>      if (!oc) {
> +        char *module_name;
>          module_load_qom_one(typename);
>          oc = object_class_by_name(typename);
> +        module_name = get_accel_module_name(typename);
> +        if (module_name) {
> +            if (!module_is_loaded(module_name)) {
> +                fprintf(stderr, "%s module is missing, install the "
> +                                "package or config the library path "
> +                                "correctly.\n", module_name);
> +                g_free(module_name);
> +                exit(1);
> +            }
> +            g_free(module_name);
> +        }
>      }
>  #endif
>      return oc;
> 

Hi Jose,

this inserts accel logic into module_object_class_by_name,
maybe some other place would be better to insert this check,
like when trying to select an accelerator?

Thanks,

CLaudio