[PATCH 1/1] riscv: support building double-float modules

Heinrich Schuchardt
2022-10-08T09:18:08Z

The riscv32 toolchain for GCC-12 provided by kernel.org contains libgcc.a
compiled for double-float. To link to it we have to adjust how we build
U-Boot.

As U-Boot actually does not use floating point at all this should not
make a significant difference for the produced binaries.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
---
arch/riscv/Kconfig | 14 ++++++++++++++
arch/riscv/Makefile | 17 ++++++++++++++---
2 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 32a90b83b5..8add95c8ef 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -152,6 +152,20 @@ config RISCV_ISA_C
when building U-Boot, which results in compressed instructions in the
U-Boot binary.

+config RISCV_ISA_F
+ bool "Standard extension for Single-Precision Floating Point"
+ default y
+ help
+ Adds "F" to the ISA string passed to the compiler.
+
+config RISCV_ISA_D
+ bool "Standard extension forr Double-Precision Floating Point"
+ depends on RISCV_ISA_F
+ default y
+ help
+ Adds "D" to the ISA string passed to the compiler and changes the
+ riscv32 ABI from ilp32 to ipl32d.
+
config RISCV_ISA_A
def_bool y

diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
index 53d1194ffb..d1b6e86dd8 100644
--- a/arch/riscv/Makefile
+++ b/arch/riscv/Makefile
@@ -5,15 +5,24 @@

ifeq ($(CONFIG_ARCH_RV64I),y)
ARCH_BASE = rv64im
- ABI = lp64
+ ABI_BASE = lp64
endif
ifeq ($(CONFIG_ARCH_RV32I),y)
ARCH_BASE = rv32im
- ABI = ilp32
+ ABI_BASE = ilp32
endif
ifeq ($(CONFIG_RISCV_ISA_A),y)
ARCH_A = a
endif
+ifeq ($(CONFIG_RISCV_ISA_F),y)
+ ARCH_F = f
+endif
+ifeq ($(CONFIG_RISCV_ISA_D),y)
+ ARCH_D = d
+ifeq ($(CONFIG_ARCH_RV32I),y)
+ ABI_D = d
+endif
+endif
ifeq ($(CONFIG_RISCV_ISA_C),y)
ARCH_C = c
endif
@@ -24,7 +33,9 @@ ifeq ($(CONFIG_CMODEL_MEDANY),y)
CMODEL = medany
endif

-RISCV_MARCH = $(ARCH_BASE)$(ARCH_A)$(ARCH_C)
+
+RISCV_MARCH = $(ARCH_BASE)$(ARCH_A)$(ARCH_F)$(ARCH_D)$(ARCH_C)
+ABI = $(ABI_BASE)$(ABI_D)

# Newer binutils versions default to ISA spec version 20191213 which moves some
# instructions from the I extension to the Zicsr and Zifencei extensions.
--
2.37.2