efi的sys文件系統接口

2019-11-09 16:54:51

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在driver/firmware/efi/efi.c 中通過subsys_initcall(efisubsys_init);來初始化efisubsysstatic int __init efisubsys_init(void){ int error; if (!efi_enabled(EFI_BOOT)) return 0; /* We register the efi directory at /sys/firmware/efi */ efi_kobj = kobject_create_and_add("efi", firmware_kobj); if (!efi_kobj) { PR_err("efi: Firmware registration failed./n"); return -ENOMEM; } error = generic_ops_register(); if (error) goto err_put; if (efi_enabled(EFI_RUNTIME_SERVICES)) efivar_ssdt_load(); error = sysfs_create_group(efi_kobj, &efi_subsys_attr_group); if (error) { pr_err("efi: Sysfs attribute export failed with error %d./n", error); goto err_unregister; } error = efi_runtime_map_init(efi_kobj); if (error) goto err_remove_group; /* and the standard mountpoint for efivarfs */ error = sysfs_create_mount_point(efi_kobj, "efivars"); if (error) { pr_err("efivars: Subsystem registration failed./n"); goto err_remove_group; }}在efisubsys_init 中會通過kobject_create_and_add在/sys/firmware/下建立efi的目錄，然后會通過sysfs_create_group來efi_subsys_attr_group groupstatic struct attribute_group efi_subsys_attr_group = { .attrs = efi_subsys_attrs, .is_visible = efi_attr_is_visible,};繼續看efi_subsys_attrs static struct attribute *efi_subsys_attrs[] = { &efi_attr_systab.attr, &efi_attr_fw_vendor.attr, &efi_attr_runtime.attr, &efi_attr_config_table.attr, &efi_attr_fw_platform_size.attr, NULL,};在efisubsys_init 中通過sysfs_create_mount_point 來創建efivars的mountpoint。而efi_runtime_map_init 則為每一段efi.memmap 創建sys接口，而所有的接口都是放在map_entries 這個list中int __init efi_runtime_map_init(struct kobject *efi_kobj){ int i, j, ret = 0; struct efi_runtime_map_entry *entry; efi_memory_desc_t *md; if (!efi_enabled(EFI_MEMMAP)) return 0; map_entries = kzalloc(efi.memmap.nr_map * sizeof(entry), GFP_KERNEL); if (!map_entries) { ret = -ENOMEM; goto out; } i = 0; for_each_efi_memory_desc(md) { entry = add_sysfs_runtime_map_entry(efi_kobj, i, md); if (IS_ERR(entry)) { ret = PTR_ERR(entry); goto out_add_entry; } *(map_entries + i++) = entry; } return 0;out_add_entry: for (j = i - 1; j >= 0; j--) { entry = *(map_entries + j); kobject_put(&entry->kobj); }out: return ret;}因此實際我們可以看到如下：[root@CentOS efi]# pwd/sys/firmware/efi[root@CentOS efi]# lsefivars fw_platform_size systab vars

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