efi_loader: comments for efi_install_fdt()

Describe that efi_install_fdt() defaults to using the device tree
indicated by environment variable fdtcontroladdr.

ACPI tables and device trees are mutually exclusive.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

diff --git a/cmd/bootefi.c b/cmd/bootefi.c
index 0b3c5cdb902a450c3ac930d5f7b41d761d461780..c19256e00dc9bff711e45d5dd65311a736c27dbe 100644 (file)
--- a/cmd/bootefi.c
+++ b/cmd/bootefi.c
@@ -196,11 +196,16 @@ static void *get_config_table(const efi_guid_t *guid)
 
 /**
  * efi_install_fdt() - install fdt passed by a command argument
+ *
+ * If fdt_opt is available, the device tree located at that memory address will
+ * will be installed as configuration table, otherwise the device tree located
+ * at the address indicated by environment variable fdtcontroladdr will be used.
+ *
+ * On architectures (x86) using ACPI tables device trees shall not be installed
+ * as configuration table.
+ *
  * @fdt_opt:   pointer to argument
  * Return:     status code
- *
- * If specified, fdt will be installed as configuration table,
- * otherwise no fdt will be passed.
  */
 static efi_status_t efi_install_fdt(const char *fdt_opt)
 {