[U-Boot] [PATCH v2 07/29] riscv: add Kconfig entries for the code model

[Lukas Auer]

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.auer at 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