[PATCH 1/1] sandbox: allow cross-compiling sandbox

[Heinrich Schuchardt]

UEFI test files like helloworld.efi require an architecture specific
PE-COFF header.

For non-sandbox the PE-COFF header is chosen by the target architecture.
For the sandbox we use the host architecture. This is not helpful for cross
compiling. Allow specifying the target architecture of the sandbox via
environment variable MK_ARCH, e.g.

    make sandbox_defconfig NO_SDL=1
    CROSS_COMPILE=aarch64-linux-gnu- NO_SDL=1 MK_ARCH=aarch64 make

Signed-off-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
---
 Makefile             |  2 +-
 doc/arch/sandbox.rst | 14 ++++++++++++++
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index 23dd11f723..286e5148ae 100644
--- a/Makefile
+++ b/Makefile
@@ -19,7 +19,7 @@ MAKEFLAGS += -rR --include-dir=$(CURDIR)

 # Determine host architecture
 include include/host_arch.h
-MK_ARCH="${shell uname -m}"
+MK_ARCH?="${shell uname -m}"
 unexport HOST_ARCH
 ifeq ("x86_64", $(MK_ARCH))
   export HOST_ARCH=$(HOST_ARCH_X86_64)
diff --git a/doc/arch/sandbox.rst b/doc/arch/sandbox.rst
index 60ee1e0741..0dd9edc8cb 100644
--- a/doc/arch/sandbox.rst
+++ b/doc/arch/sandbox.rst
@@ -33,6 +33,20 @@ integers can only be built on 64-bit hosts.

 Note that standalone/API support is not available at present.

+Cross compiling
+---------------
+
+When cross compiling the U-Boot sandbox with CONFIG_EFI_LOADER=y the target
+architecture must be specified using the MK_ARCH environment variable using one
+of the values aarch64, armv7l, i386, riscv32, riscv64, x86_64, e.g.
+
+.. code-block:: bash
+
+    NO_SDL=1 make sandbox_defconfig
+    CROSS_COMPILE=aarch64-linux-gnu- MK_ARCH=aarch64 NO_SDL=1 make
+
+NO_SDL=1 was chosen in the example to remove the dependency on the SDL library.
+The graphical console will not be available.

 Prerequisites
 -------------
--
2.30.0