----- Forwarded message from Yimin Gu ustcymgu@gmail.com -----

Date: Thu, 10 Mar 2022 19:57:03 +0800 From: Yimin Gu ustcymgu@gmail.com To: devel@uclibc-ng.org Cc: wbx@uclibc-ng.org Subject: [PATCH] Enable build for RISC-V 32-bit target

RISC-V 32-bit No-MMU is not officially supported by Linux kernel, but the current 64-bit toolchain can be built for 32-bit targets without substantial code change, thus it's nice to let uclibc compile for rv32 targets. I also managed to get uclibc/busybox running on rv32 QEMU and FPGA softcore without noticable problem based on this: https://github.com/damien-lemoal/buildroot. Note that to compile successfully, these macros need to be added in the arch/riscv/include/uapi/asm/unistd.h kernel header file:

#define __ARCH_WANT_NEW_STAT #define __ARCH_WANT_SET_GET_RLIMIT #define __ARCH_WANT_TIME32_SYSCALLS

Signed-off-by: Yimin Gu ustcymgu@gmail.com --- libc/sysdeps/linux/riscv64/bits/wordsize.h | 3 ++- libc/sysdeps/linux/riscv64/sys/asm.h | 6 +++++- 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/libc/sysdeps/linux/riscv64/bits/wordsize.h b/libc/sysdeps/linux/riscv64/bits/wordsize.h index 67a16ba62..1fc649aad 100644 --- a/libc/sysdeps/linux/riscv64/bits/wordsize.h +++ b/libc/sysdeps/linux/riscv64/bits/wordsize.h @@ -25,5 +25,6 @@ #if __riscv_xlen == 64 # define __WORDSIZE_TIME64_COMPAT32 1 #else -# error "rv32i-based targets are not supported" +# define __WORDSIZE_TIME64_COMPAT32 1 +// # warning "rv32i-based targets are experimental" #endif diff --git a/libc/sysdeps/linux/riscv64/sys/asm.h b/libc/sysdeps/linux/riscv64/sys/asm.h index ddb84b683..3d0f7afbc 100644 --- a/libc/sysdeps/linux/riscv64/sys/asm.h +++ b/libc/sysdeps/linux/riscv64/sys/asm.h @@ -26,7 +26,11 @@ # define REG_S sd # define REG_L ld #elif __riscv_xlen == 32 -# error "rv32i-based targets are not supported" +# warning "rv32i-based targets are experimental" +# define PTRLOG 2 +# define SZREG 4 +# define REG_S sw +# define REG_L lw #else # error __riscv_xlen must equal 32 or 64 #endif