Bootloader may need to fixup the device tree before OS can use it.
Therefore, install fdt used by OS in configuration tables and associate it
with device tree guid.
UEFI/DXE drivers can fixup this device tree in their respective
ExitBootServices events.
Cc: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Cc: linux-efi@xxxxxxxxxxxxxxx
Signed-off-by: Pankaj Bansal <pankaj.bansal@xxxxxxx>
---
Notes:
V2:
- Add a check while installing fdt in configuration table, that
new_fdt would only be installed in configuration table if it
has been generated using fdt already present in configuration table.
drivers/firmware/efi/libstub/fdt.c | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/drivers/firmware/efi/libstub/fdt.c b/drivers/firmware/efi/libstub/fdt.c
index 45cded5b5d5c..dc228c05d0cd 100644
--- a/drivers/firmware/efi/libstub/fdt.c
+++ b/drivers/firmware/efi/libstub/fdt.c
@@ -269,6 +269,9 @@ efi_status_t allocate_new_fdt_and_exit_boot(efi_system_table_t *sys_table_arg,
int runtime_entry_count = 0;
struct efi_boot_memmap map;
struct exit_boot_struct priv;
+ efi_guid_t fdt_guid = DEVICE_TREE_GUID;
+ unsigned long fdt_config_table_addr = 0;
+ unsigned long fdt_config_table_size = 0;
map.map = &runtime_map;
map.map_size = &map_size;
@@ -318,6 +321,23 @@ efi_status_t allocate_new_fdt_and_exit_boot(efi_system_table_t *sys_table_arg,
goto fail_free_new_fdt;
}
+ /* Determine if the fdt_addr is obtained from uefi configuration
+ * table or not? if yes, then install the new_fdt_addr in configuration
+ * table in its place, as the UEFI firmware may need to modify it
+ * as part of exit_boot_services routine
+ */
+ fdt_config_table_addr = (uintptr_t)get_fdt(sys_table_arg,
+ &fdt_config_table_size);
+ if ((fdt_config_table_size == fdt_size) &&
+ (fdt_config_table_addr == fdt_addr)) {
+ status = efi_call_early(install_configuration_table, &fdt_guid,
+ (void *)*new_fdt_addr);
+ if (status != EFI_SUCCESS) {
+ pr_efi_err(sys_table_arg, "Unable to install new device tree.\n");
+ goto fail_free_new_fdt;
+ }
+ }
+
priv.runtime_map = runtime_map;
priv.runtime_entry_count = &runtime_entry_count;
priv.new_fdt_addr = (void *)*new_fdt_addr;
--
2.17.1
