From 4a503484aa0e2615add92f0e2e014ea26bb6dff1 Mon Sep 17 00:00:00 2001
From: kevin <kevin@deepai.org>
Date: Wed, 30 Sep 2026 18:36:21 +0000
Subject: [PATCH] [bsp][qemu-virt64-riscv] Allow optional C-only Picolibc
 builds

---
 bsp/qemu-virt64-riscv/SConstruct  | 3 +++
 bsp/qemu-virt64-riscv/rtconfig.py | 3 +++
 2 files changed, 6 insertions(+)

diff --git a/bsp/qemu-virt64-riscv/SConstruct b/bsp/qemu-virt64-riscv/SConstruct
index ae0e3375e111..71e1b82dea06 100644
--- a/bsp/qemu-virt64-riscv/SConstruct
+++ b/bsp/qemu-virt64-riscv/SConstruct
@@ -27,6 +27,9 @@ rtconfig.ARCH='risc-v'
 # prepare building environment
 objs = PrepareBuilding(env, RTT_ROOT, has_libcpu = False)
 
+if not GetDepend('RT_USING_CPLUSPLUS'):
+    env['LINKFLAGS'] = env['LINKFLAGS'].replace(' -lsupc++', '')
+
 stack_size = 4096
 
 if GetDepend('RT_USING_SMART'):
diff --git a/bsp/qemu-virt64-riscv/rtconfig.py b/bsp/qemu-virt64-riscv/rtconfig.py
index 09d530af4a1c..82d1719efd38 100644
--- a/bsp/qemu-virt64-riscv/rtconfig.py
+++ b/bsp/qemu-virt64-riscv/rtconfig.py
@@ -33,6 +33,9 @@
     OBJCPY  = PREFIX + 'objcopy'
 
     DEVICE  = ' -mcmodel=medany -march=rv64imafdc -mabi=lp64 '
+    # Optional Picolibc toolchain; leave the default libc selection unchanged.
+    if os.getenv('RTT_PICOLIBC_SPECS'):
+        DEVICE += '--specs=' + os.environ['RTT_PICOLIBC_SPECS'] + ' '
     CFLAGS  = DEVICE + '-ffreestanding -flax-vector-conversions -Wno-cpp -fno-common -ffunction-sections -fdata-sections -fstrict-volatile-bitfields -fdiagnostics-color=always'
     AFLAGS  = ' -c' + DEVICE + ' -x assembler-with-cpp -D__ASSEMBLY__ '
     LFLAGS  = DEVICE + ' -nostartfiles -Wl,--gc-sections,-Map=rtthread.map,-cref,-u,_start -T link.lds' + ' -lsupc++ -lgcc -static'