efi_loader: Add OS notifications for SetVariable at runtime
Previous patches enable SetVariable at runtime using a volatile storage
backend using EFI_RUNTIME_SERVICES_DATA allocared memory. Since there's
no recommendation from the spec on how to notify the OS, add a volatile
EFI variable that contains the filename relative to the ESP. OS'es
can use that file and update it at runtime
$~ efivar -p -n b2ac5fc9-92b7-4acd-aeac-11e818c3130c-RTStorageVolatile
GUID: b2ac5fc9-92b7-4acd-aeac-11e818c3130c
Name: "RTStorageVolatile"
Attributes:
Boot Service Access
Runtime Service Access
Value:
00000000 75 62 6f 6f 74 65 66 69 2e 76 61 72 00 |ubootefi.var. |
Reviewed-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
diff --git a/lib/efi_loader/efi_runtime.c b/lib/efi_loader/efi_runtime.c
index dde083b..c8f7a88 100644
--- a/lib/efi_loader/efi_runtime.c
+++ b/lib/efi_loader/efi_runtime.c
@@ -10,6 +10,7 @@
#include <dm.h>
#include <elf.h>
#include <efi_loader.h>
+#include <efi_variable.h>
#include <log.h>
#include <malloc.h>
#include <rtc.h>
@@ -110,6 +111,7 @@
*/
efi_status_t efi_init_runtime_supported(void)
{
+ const efi_guid_t efi_guid_efi_rt_var_file = U_BOOT_EFI_RT_VAR_FILE_GUID;
efi_status_t ret;
struct efi_rt_properties_table *rt_table;
@@ -127,9 +129,20 @@
EFI_RT_SUPPORTED_SET_VIRTUAL_ADDRESS_MAP |
EFI_RT_SUPPORTED_CONVERT_POINTER;
- if (IS_ENABLED(CONFIG_EFI_RT_VOLATILE_STORE))
- rt_table->runtime_services_supported |=
- EFI_RT_SUPPORTED_SET_VARIABLE;
+ if (IS_ENABLED(CONFIG_EFI_RT_VOLATILE_STORE)) {
+ ret = efi_set_variable_int(u"RTStorageVolatile",
+ &efi_guid_efi_rt_var_file,
+ EFI_VARIABLE_BOOTSERVICE_ACCESS |
+ EFI_VARIABLE_RUNTIME_ACCESS |
+ EFI_VARIABLE_READ_ONLY,
+ sizeof(EFI_VAR_FILE_NAME),
+ EFI_VAR_FILE_NAME, false);
+ if (ret != EFI_SUCCESS) {
+ log_err("Failed to set RTStorageVolatile\n");
+ return ret;
+ }
+ rt_table->runtime_services_supported |= EFI_RT_SUPPORTED_SET_VARIABLE;
+ }
/*
* This value must be synced with efi_runtime_detach_list