RISC-V has two code models, medium low (medlow) and medium any (medany).
Medlow limits addressable memory to a single 2 GiB range between the
absolute addresses -2 GiB and +2 GiB. Medany limits addressable memory
to any single 2 GiB address range.
By default, medlow is selected on 32-bit systems and medany on 64-bit
systems. This matches the configuration in Linux.
The -mcmodel compiler flag is selected according to the Kconfig
configuration.
Signed-off-by: Lukas Auer <lukas.a...@aisec.fraunhofer.de>
---
Changes in v2:
- Change ISA string construction, as suggested by Bin Meng
arch/riscv/Kconfig | 19 +++++++++++++++++++
arch/riscv/Makefile | 9 ++++++++-
2 files changed, 27 insertions(+), 1 deletion(-)
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 0de77a75d7..371921b412 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -38,6 +38,25 @@ config ARCH_RV64I
endchoice
+choice
+ prompt "Code Model"
+ default CMODEL_MEDLOW if 32BIT
+ default CMODEL_MEDANY if 64BIT
+
+config CMODEL_MEDLOW
+ bool "medium low code model"
+ help
+ U-Boot and its statically defined symbols must lie within a single 2
GiB
+ address range and must lie between absolute addresses -2 GiB and +2
GiB.
+
+config CMODEL_MEDANY
+ bool "medium any code model"
+ help
+ U-Boot and its statically defined symbols must be within any single 2
GiB
+ address range.
+
+endchoice
+
config RISCV_ISA_C
bool "Emit compressed instructions"
default y
diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
index 55d7c6550e..0b80eb8d86 100644
--- a/arch/riscv/Makefile
+++ b/arch/riscv/Makefile
@@ -17,8 +17,15 @@ endif
ifeq ($(CONFIG_RISCV_ISA_C),y)
ARCH_C = c
endif
+ifeq ($(CONFIG_CMODEL_MEDLOW),y)
+ CMODEL = medlow
+endif
+ifeq ($(CONFIG_CMODEL_MEDANY),y)
+ CMODEL = medany
+endif
-ARCH_FLAGS = -march=$(ARCH_BASE)$(ARCH_A)$(ARCH_C) -mabi=$(ABI)
+ARCH_FLAGS = -march=$(ARCH_BASE)$(ARCH_A)$(ARCH_C) -mabi=$(ABI) \
+ -mcmodel=$(CMODEL)
PLATFORM_CPPFLAGS += $(ARCH_FLAGS)
CFLAGS_EFI += $(ARCH_FLAGS)
--
2.17.2
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