On Thu, Oct 12, 2023 at 02:48:50PM +0100, Alan Maguire wrote:
> On 12/10/2023 13:53, Jiri Olsa wrote:
> > On Wed, Oct 11, 2023 at 10:17:31AM +0100, Alan Maguire wrote:
> >
> > SNIP
> >
> >> +#define BTF_FEATURE(name, alias, skip) \
> >> + { #name, #alias, offsetof(struct conf_load, alias), skip }
> >> +
> >> +struct btf_feature {
> >> + const char *name;
> >> + const char *option_alias;
> >> + size_t conf_load_offset;
> >> + bool skip;
> >> +} btf_features[] = {
> >> + BTF_FEATURE(encode_force, btf_encode_force, false),
> >> + BTF_FEATURE(var, skip_encoding_btf_vars, true),
> >> + BTF_FEATURE(float, btf_gen_floats, false),
> >> + BTF_FEATURE(decl_tag, skip_encoding_btf_decl_tag, true),
> >> + BTF_FEATURE(type_tag, skip_encoding_btf_type_tag, true),
> >> + BTF_FEATURE(enum64, skip_encoding_btf_enum64, true),
> >> + BTF_FEATURE(optimized, btf_gen_optimized, false),
> >> + /* the "skip" in skip_encoding_btf_inconsistent_proto is misleading
> >> + * here; this is a positive feature to ensure consistency of
> >> + * representation rather than a negative option which we want
> >> + * to invert. So as a result, "skip" is false here.
> >> + */
> >> + BTF_FEATURE(consistent, skip_encoding_btf_inconsistent_proto, false),
> >> +};
> >> +
> >> +#define BTF_MAX_FEATURES 32
> >> +#define BTF_MAX_FEATURE_STR 256
> >> +
> >> +/* Translate --btf_features=feature1[,feature2] into conf_load values.
> >> + * Explicitly ignores unrecognized features to allow future specification
> >> + * of new opt-in features.
> >> + */
> >> +static void parse_btf_features(const char *features, struct conf_load *conf_load)
> >> +{
> >> + char *feature_list[BTF_MAX_FEATURES] = {};
> >> + char f[BTF_MAX_FEATURE_STR];
> >> + bool encode_all = false;
> >> + int i, j, n = 0;
> >> +
> >> + strncpy(f, features, sizeof(f));
> >> +
> >> + if (strcmp(features, "all") == 0) {
> >> + encode_all = true;
> >> + } else {
> >> + char *saveptr = NULL, *s = f, *t;
> >> +
> >> + while ((t = strtok_r(s, ",", &saveptr)) != NULL) {
> >> + s = NULL;
> >> + feature_list[n++] = t;
> >> + }
> >> + }
> >> +
> >> + for (i = 0; i < ARRAY_SIZE(btf_features); i++) {
> >> + bool *bval = (bool *)(((void *)conf_load) + btf_features[i].conf_load_offset);
> >
> > nit, would it be easier to have btf_features defined inside the function
> > and pass specific bool pointers directly to BTF_FEATURE macro?
> >
>
> thanks for taking a look! I _think_ I see what you mean; if we had
> conf_load we could encode the bool pointer directly using
> the BTF_FEATURE() definition, something like
>
> #define BTF_FEATURE(name, alias, default_value) \
> { #name, #alias, &conf_load->alias, default_value }
>
> struct btf_feature {
> const char *name;
> const char *option_alias;
> bool *conf_value;
> bool default_value;
> } btf_features[] = {
> ...
>
> This will work I think because conf_load is a global variable,
yes, it's global, but it's also passed as an argument to parse_btf_features,
so it could be done on top of that conf_load pointer
> and I think we need to keep it global since it's also used by
> patch 4 to get the list of supported features. Is the above
> something like what you had in mind? Thanks!
yes, using the bools directly
thanks,
jirka
