[PATCH v2 4/7] linux: ignore FDT unless we need to modify it

[Nikita Ermakov <arei@altlinux.org>]

From: Ard Biesheuvel <ard.biesheuvel@arm.com>

Now that we implemented supported for the LoadFile2 protocol for initrd
loading, there is no longer a need to pass the initrd parameters via
the device tree. This means there is no longer a reason to update the
device tree in the first place, and so we can ignore it entirely.

The only remaining reason to deal with the devicetree is if we are
using the 'devicetree' command to load one from disk, so tweak the
logic in grub_fdt_install() to take that into account.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@arm.com>
---
 grub-core/loader/arm64/linux.c | 22 +++++++++++-----------
 grub-core/loader/efi/fdt.c     |  7 +++++--
 2 files changed, 16 insertions(+), 13 deletions(-)

diff --git a/grub-core/loader/arm64/linux.c b/grub-core/loader/arm64/linux.c
index 6b03455d1..65f1275fb 100644
--- a/grub-core/loader/arm64/linux.c
+++ b/grub-core/loader/arm64/linux.c
@@ -95,21 +95,21 @@ finalize_params_linux (void)
 
   void *fdt;
 
-  fdt = grub_fdt_load (GRUB_EFI_LINUX_FDT_EXTRA_SPACE);
+  /* Set initrd info */
+  if (initrd_start && initrd_end > initrd_start)
+    {
+      fdt = grub_fdt_load (GRUB_EFI_LINUX_FDT_EXTRA_SPACE);
 
-  if (!fdt)
-    goto failure;
+      if (!fdt)
+	goto failure;
 
-  node = grub_fdt_find_subnode (fdt, 0, "chosen");
-  if (node < 0)
-    node = grub_fdt_add_subnode (fdt, 0, "chosen");
+      node = grub_fdt_find_subnode (fdt, 0, "chosen");
+      if (node < 0)
+	node = grub_fdt_add_subnode (fdt, 0, "chosen");
 
-  if (node < 1)
-    goto failure;
+      if (node < 1)
+	goto failure;
 
-  /* Set initrd info */
-  if (initrd_start && initrd_end > initrd_start)
-    {
       grub_dprintf ("linux", "Initrd @ %p-%p\n",
 		    (void *) initrd_start, (void *) initrd_end);
 
diff --git a/grub-core/loader/efi/fdt.c b/grub-core/loader/efi/fdt.c
index c86f283d7..771d455c7 100644
--- a/grub-core/loader/efi/fdt.c
+++ b/grub-core/loader/efi/fdt.c
@@ -89,13 +89,16 @@ grub_fdt_install (void)
   grub_efi_guid_t fdt_guid = GRUB_EFI_DEVICE_TREE_GUID;
   grub_efi_status_t status;
 
+  if (!fdt && !loaded_fdt)
+    return GRUB_ERR_NONE;
+
   b = grub_efi_system_table->boot_services;
-  status = b->install_configuration_table (&fdt_guid, fdt);
+  status = b->install_configuration_table (&fdt_guid, fdt ?: loaded_fdt);
   if (status != GRUB_EFI_SUCCESS)
     return grub_error (GRUB_ERR_IO, "failed to install FDT");
 
   grub_dprintf ("fdt", "Installed/updated FDT configuration table @ %p\n",
-		fdt);
+		fdt ?: loaded_fdt);
   return GRUB_ERR_NONE;
 }
 
-- 
2.29.3