[PATCH v10 3/4] Boot var automatic management for removable medias

[Raymond Mao]

Changes for complying to EFI spec §3.5.1.1
'Removable Media Boot Behavior'.
Boot variables can be automatically generated during a removable
media is probed. At the same time, unused boot variables will be
detected and removed.

Please note that currently the function 'efi_disk_remove' has no
ability to distinguish below two scenarios
a) Unplugging of a removable media under U-Boot
b) U-Boot exiting and booting an OS
Thus currently the boot variables management is not added into
'efi_disk_remove' to avoid boot options being added/erased
repeatedly under scenario b) during power cycles
See TODO comments under function 'efi_disk_remove' for more details

Signed-off-by: Raymond Mao <raymond.mao at linaro.org>
---
Changes in v3
- Split the patch into moving and renaming functions and
  individual patches for each changed functionality
Changes in v5
- Move function call of efi_bootmgr_update_media_device_boot_option()
  from efi_init_variables() to efi_init_obj_list()
Changes in v6
- Revert unrelated changes
Changes in v7
- adapt the return code of function
  efi_bootmgr_update_media_device_boot_option()
Changes in v8
- add a note in the commit message for future reference
Changes in v9
- amend the note text in the commit message
- add a TODO comment in 'efi_disk_remove'
Changes in v10
- fix typo and build failures with 'CONFIG_CMD_BOOTEFI_BOOTMGR=n'

 lib/efi_loader/efi_disk.c  | 18 ++++++++++++++++++
 lib/efi_loader/efi_setup.c |  7 +++++++
 2 files changed, 25 insertions(+)

diff --git a/lib/efi_loader/efi_disk.c b/lib/efi_loader/efi_disk.c
index d2256713a8..911a4adfb1 100644
--- a/lib/efi_loader/efi_disk.c
+++ b/lib/efi_loader/efi_disk.c
@@ -687,6 +687,13 @@ int efi_disk_probe(void *ctx, struct event *event)
 			return -1;
 	}
 
+	/* only do the boot option management when UEFI sub-system is initialized */
+	if (IS_ENABLED(CONFIG_CMD_BOOTEFI_BOOTMGR) && efi_obj_list_initialized == EFI_SUCCESS) {
+		ret = efi_bootmgr_update_media_device_boot_option();
+		if (ret != EFI_SUCCESS)
+			return -1;
+	}
+
 	return 0;
 }
 
@@ -773,6 +780,17 @@ int efi_disk_remove(void *ctx, struct event *event)
 		return efi_disk_delete_part(dev);
 	else
 		return 0;
+
+	/*
+	 * TODO A flag to distinguish below 2 different scenarios of this
+	 * function call is needed:
+	 * a) Unplugging of a removable media under U-Boot
+	 * b) U-Boot exiting and booting an OS
+	 * In case of scenario a), efi_bootmgr_update_media_device_boot_option()
+	 * needs to be invoked here to update the boot options and remove the
+	 * unnecessary ones.
+	 */
+
 }
 
 /**
diff --git a/lib/efi_loader/efi_setup.c b/lib/efi_loader/efi_setup.c
index 58d4e13402..69c8b27730 100644
--- a/lib/efi_loader/efi_setup.c
+++ b/lib/efi_loader/efi_setup.c
@@ -245,6 +245,13 @@ efi_status_t efi_init_obj_list(void)
 	if (ret != EFI_SUCCESS)
 		goto out;
 
+	if (IS_ENABLED(CONFIG_CMD_BOOTEFI_BOOTMGR)) {
+		/* update boot option after variable service initialized */
+		ret = efi_bootmgr_update_media_device_boot_option();
+		if (ret != EFI_SUCCESS)
+			goto out;
+	}
+
 	/* Define supported languages */
 	ret = efi_init_platform_lang();
 	if (ret != EFI_SUCCESS)
-- 
2.25.1