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riscv: add Kconfig entries for the code model

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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 for U-Boot on both 32-bit and 64-bit
systems.

The -mcmodel compiler flag is selected according to the Kconfig
configuration.

Signed-off-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
[bmeng: adjust to make medlow the default code model for U-Boot]
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
This commit is contained in:
Lukas Auer 2018-12-12 06:12:23 -08:00 committed by Andes
parent 1f2e948d6d
commit 8176ea4d58
2 changed files with 26 additions and 1 deletions
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18
arch/riscv/Kconfig
View File

@ -44,6 +44,24 @@ config ARCH_RV64I
endchoice
choice
prompt "Code Model"
default CMODEL_MEDLOW
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

9
arch/riscv/Makefile
View File

@ -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)