[PATCH] efi: Make FDT extra space configurable

[Pawel Kochanowski]

From: Gabriel Nesteruk <gnesteruk at sii.pl>

U-Boot currently reserves only 0x3000 bytes when copying the FDT
in `copy_fdt()`, which may not be sufficient if additional nodes
(such as FMAN firmware) are added later.

This patch introduces a new `CONFIG_FDT_EXTRA_SPACE` Kconfig option
to allow users to define the amount of extra space reserved for FDT
expansion. The default remains 0x3000.

This change prevents potential corruption when resizing FDT after
EFI boot, especially when firmware like FMAN requires additional
space.

Signed-off-by: Gabriel Nesteruk <gnesteruk at sii.pl>
Signed-off-by: Pawel Kochanowski <pkochanowski at sii.pl>
---
 lib/efi_loader/Kconfig      | 9 +++++++++
 lib/efi_loader/efi_helper.c | 2 +-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig
index d4f6b56afaa..bd2cbe995c9 100644
--- a/lib/efi_loader/Kconfig
+++ b/lib/efi_loader/Kconfig
@@ -586,6 +586,15 @@ config BOOTEFI_TESTAPP_COMPILE
 	  No additional space will be required in the resulting U-Boot binary
 	  when this option is enabled.
 
+config EFI_FDT_EXTRA_SPACE
+    hex "Extra space to allocate for FDT expansion"
+    default 0x3000
+    help
+      Defines additional space (in bytes) reserved for expanding the
+      Flattened Device Tree (FDT) when passed to the EFI system.
+      Increase this value if your firmware (e.g., FMAN) needs to add
+      more data to the device tree after U-Boot relocation.
+
 endif
 
 source "lib/efi/Kconfig"
diff --git a/lib/efi_loader/efi_helper.c b/lib/efi_loader/efi_helper.c
index 04b2efc4a3b..91b2a5b8653 100644
--- a/lib/efi_loader/efi_helper.c
+++ b/lib/efi_loader/efi_helper.c
@@ -477,7 +477,7 @@ static efi_status_t copy_fdt(void **fdtp)
 	 * needs to be expanded later.
 	 */
 	fdt = *fdtp;
-	fdt_pages = efi_size_in_pages(fdt_totalsize(fdt) + 0x3000);
+	fdt_pages = efi_size_in_pages(fdt_totalsize(fdt) + CONFIG_EFI_FDT_EXTRA_SPACE);
 	fdt_size = fdt_pages << EFI_PAGE_SHIFT;
 
 	ret = efi_allocate_pages(EFI_ALLOCATE_ANY_PAGES,
-- 
2.43.0