[Concept,06/13] ulib: x86: Add 32-bit Rust target support
Commit Message
From: Simon Glass <simon.glass@canonical.com>
There is no built-in i686-unknown-none Rust target, so use
i686-unknown-linux-gnu with flags to disable unwinding and force
static relocations, which produces a clean freestanding ELF 32-bit
object suitable for linking into U-Boot.
Select the Rust target and flags based on CONFIG_X86_64 so that the
64-bit build continues to use x86_64-unknown-none with its built-in
defaults (PIE-compatible code, no unwinding).
Co-developed-by: Claude Opus 4.6 <noreply@anthropic.com>
Signed-off-by: Simon Glass <simon.glass@canonical.com>
---
scripts/Makefile.ulib-example | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
@@ -21,8 +21,18 @@ ULIB_EXAMPLES := demo
# --- Rust examples ---
RUSTC := rustc
-RUST_TARGET_x86 := x86_64-unknown-none
+RUST_TARGET_x86 := i686-unknown-linux-gnu
+RUST_TARGET_x86_64 := x86_64-unknown-none
+RUST_FLAGS_x86 := -C panic=abort -C relocation-model=static
+RUST_FLAGS_x86_64 :=
+
+ifdef CONFIG_X86_64
+RUST_TARGET := $(RUST_TARGET_$(EXAMPLE_ARCH)_64)
+RUST_FLAGS := $(RUST_FLAGS_$(EXAMPLE_ARCH)_64)
+else
RUST_TARGET := $(RUST_TARGET_$(EXAMPLE_ARCH))
+RUST_FLAGS := $(RUST_FLAGS_$(EXAMPLE_ARCH))
+endif
ifeq ($(CONFIG_RUST_EXAMPLES),y)
ULIB_EXAMPLES += rust-demo
@@ -34,7 +44,8 @@ quiet_cmd_u-boot-example = LD $@
quiet_cmd_rustc_obj = RUSTC $@
cmd_rustc_obj = \
mkdir -p $(dir $@) && \
- MAKEFLAGS= $(RUSTC) --edition 2021 --emit=obj -o $@ --target=$(RUST_TARGET) $<
+ MAKEFLAGS= $(RUSTC) --edition 2021 --emit=obj -o $@ \
+ --target=$(RUST_TARGET) $(RUST_FLAGS) $<
examples/ulib/rust_demo.o: examples/ulib/rust_demo.rs FORCE
$(call if_changed,rustc_obj)