Hi, I'm looking for some information about : struct kobj_attribute { struct attribute attr; ssize_t (*show)(struct kobject *kobj, struct kobj_attribute *attr, char *buf); ssize_t (*store)(struct kobject *kobj, struct kobj_attribute *attr, const char *buf, size_t count); }; My function to handle the operation: static ssize_t my_store(struct kobject *kobj, struct kobj_attribute *attr, const char *buf, size_t count) { char *buffer; buffer = (char*) kcalloc(count, sizeof(char), GFP_KERNEL); if (count == 13) { if (buffer) { copy_from_user(buffer, buf, count); printk("A %s",buffer); if (0) { if (strcmp(buffer, eudyptula_id) == 0) return count; printk("erro na strcmp\n"); } else printk("erro na copia\n"); } } return -EINVAL; } So, this *const char *buf, *where ti come from ? Kernel space -- Lucas Tanure +55 (19) 988176559