kernel中efi变量初始化

2019-11-09 17:14:10

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在setup_arch->efi_init->uefi_init->efi_config_parse_tablesint __init efi_config_parse_tables(void *config_tables, int count, int sz, efi_config_table_type_t *arch_tables){ void *tablep; int i; tablep = config_tables; PR_info(""); for (i = 0; i < count; i++) { efi_guid_t guid; unsigned long table; if (efi_enabled(EFI_64BIT)) { u64 table64; guid = ((efi_config_table_64_t *)tablep)->guid; table64 = ((efi_config_table_64_t *)tablep)->table; table = table64;#ifndef CONFIG_64BIT if (table64 >> 32) { pr_cont("/n"); pr_err("Table located above 4GB, disabling EFI./n"); return -EINVAL; }#endif } else { guid = ((efi_config_table_32_t *)tablep)->guid; table = ((efi_config_table_32_t *)tablep)->table; } if (!match_config_table(&guid, table, common_tables)) match_config_table(&guid, table, arch_tables); tablep += sz; } pr_cont("/n"); set_bit(EFI_CONFIG_TABLES, &efi.flags); /* Parse the EFI Properties table if it exists */ if (efi.properties_table != EFI_INVALID_TABLE_ADDR) { efi_properties_table_t *tbl; tbl = early_memremap(efi.properties_table, sizeof(*tbl)); if (tbl == NULL) { pr_err("Could not map Properties table!/n"); return -ENOMEM; } if (tbl->memory_protection_attribute & EFI_PROPERTIES_RUNTIME_MEMORY_PROTECTION_NON_EXECUTABLE_PE_DATA) set_bit(EFI_NX_PE_DATA, &efi.flags); early_memunmap(tbl, sizeof(*tbl)); } return 0;}在efi_config_parse_tables 中会对common_tables 中的ptr赋值，这样我们就能在kernel中使用common_tables 中的指针static __initdata efi_config_table_type_t common_tables[] = { {ACPI_20_TABLE_GUID, "ACPI 2.0", &efi.acpi20}, {ACPI_TABLE_GUID, "ACPI", &efi.acpi}, {HCDP_TABLE_GUID, "HCDP", &efi.hcdp}, {MPS_TABLE_GUID, "MPS", &efi.mps}, {SAL_SYSTEM_TABLE_GUID, "SALsystab", &efi.sal_systab}, {SMBIOS_TABLE_GUID, "SMBIOS", &efi.smbios}, {SMBIOS3_TABLE_GUID, "SMBIOS 3.0", &efi.smbios3}, {UGA_IO_PROTOCOL_GUID, "UGA", &efi.uga}, {EFI_SYSTEM_RESOURCE_TABLE_GUID, "ESRT", &efi.esrt}, {EFI_PROPERTIES_TABLE_GUID, "PROP", &efi.properties_table}, {EFI_MEMORY_ATTRIBUTES_TABLE_GUID, "MEMATTR", &efi.mem_attr_table}, {NULL_GUID, NULL, NULL},};具体是在在efi_config_parse_tables中的下面code中赋值.if (!match_config_table(&guid, table, common_tables)) match_config_table(&guid, table, arch_tables);同时会设定EFI_CONFIG_TABLES 这个flag。set_bit(EFI_CONFIG_TABLES, &efi.flags);如果uefi中有Properties table 的话，会设定set_bit(EFI_NX_PE_DATA, &efi.flags);最后补充一下，在match_config_table 中是根据guid 来找对应的table的.static __init int match_config_table(efi_guid_t *guid, unsigned long table, efi_config_table_type_t *table_types){ int i; if (table_types) { for (i = 0; efi_guidcmp(table_types[i].guid, NULL_GUID); i++) { if (!efi_guidcmp(*guid, table_types[i].guid)) { *(table_types[i].ptr) = table; if (table_types[i].name) pr_cont(" %s=0x%lx ", table_types[i].name, table); return 1; } } } return 0;}

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