rv-virt:nsh64 can't build with stock gcc-riscv64-unknown-elf on Ubuntu Jammy

[yf13]

When buildling rv-virt:nsh64 with the stock toolchain installed via sudo apt install gcc-riscv64-unknown-elf on Ubuntu 22.04, I got the following error:

$ make
./stdlib/lib_strtold.c:44:10: fatal error: math.h: No such file or directory
   44 | #include <math.h>
      |          ^~~~~~~~
compilation terminated.
ERROR: riscv64-unknown-elf-gcc failed: 1
       command: riscv64-unknown-elf-gcc -MT bin/lib_strtold.o  -M '-fno-common' '-Wall' '-Wstrict-prototypes' '-Wshadow' '-Wundef' '-Wno-attributes' '-Wno-unknown-pragmas' '-Wno-psabi' '-Os' '-fno-strict-aliasing' '-fomit-frame-pointer' '-ffunction-sections' '-fdata-sections' '-g' '-mcmodel=medany' '-march=rv64imafdc' '-mabi=lp64d' '-isystem' '/home/yf/Projects/Nuttx/nuttx/include' '-D__NuttX__' '-pipe' '-I' '/home/yf/Projects/Nuttx/nuttx/libs/libc' ./stdlib/lib_strtold.c
make[2]: *** [/home/yf/Projects/Nuttx/nuttx/tools/Config.mk:228: lib_strtold.ddc] Error 1
make[1]: *** [Makefile:189: .depend] Error 2
make: *** [tools/Unix.mk:606: pass1dep] Error 2

The toolchain has the following version info:

$ riscv64-unknown-elf-gcc -v
Using built-in specs.
COLLECT_GCC=riscv64-unknown-elf-gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/riscv64-unknown-elf/10.2.0/lto-wrapper
Target: riscv64-unknown-elf
Configured with: ../configure --build=x86_64-linux-gnu --prefix=/usr --includedir='/usr/include' --mandir='/usr/share/man' --infodir='/usr/share/info' --sysconfdir=/etc --localstatedir=/var --disable-option-checking --disable-silent-rules --libdir='/usr/lib/x86_64-linux-gnu' --libexecdir='/usr/lib/x86_64-linux-gnu' --disable-maintainer-mode --disable-dependency-tracking --target=riscv64-unknown-elf --prefix=/usr --infodir=/usr/share/doc/gcc-riscv64-unknown-elf/info --mandir=/usr/share/man --htmldir=/usr/share/doc/gcc-riscv64-unknown-elf/html --pdfdir=/usr/share/doc/gcc-riscv64-unknown-elf/pdf --bindir=/usr/bin --libexecdir=/usr/lib --libdir=/usr/lib --with-pkgversion= --disable-shared --disable-threads --enable-languages=c,c++ --enable-tls --with-newlib --with-native-system-header-dir=/include --disable-libmudflap --disable-libssp --disable-libquadmath --disable-libgomp --disable-nls --with-system-zlib --enable-checking=yes --enable-multilib --with-abi=lp64d --disable-libstdcxx-pch --disable-libstdcxx --disable-fixinc --with-arch=rv64imafdc --with-gnu-as --with-gnu-ld --with-as=/usr/lib/riscv64-unknown-elf/bin/as --with-ld=/usr/lib/riscv64-unknown-elf/bin/ld AR_FOR_TARGET=/usr/lib/riscv64-unknown-elf/bin/ar AS_FOR_TARGET=/usr/lib/riscv64-unknown-elf/bin/as NM_FOR_TARGET=/usr/lib/riscv64-unknown-elf/bin/nm LD_FOR_TARGET=/usr/lib/riscv64-unknown-elf/bin/ld OBJDUMP_FOR_TARGET=/usr/lib/riscv64-unknown-elf/bin/objdump RANLIB_FOR_TARGET=/usr/lib/riscv64-unknown-elf/bin/ranlib READELF_FOR_TARGET=/usr/lib/riscv64-unknown-elf/bin/readelf STRIP_FOR_TARGET=/usr/lib/riscv64-unknown-elf/bin/strip CFLAGS='-g -O2 -fdebug-prefix-map=/build/gcc-riscv64-unknown-elf-LkcieF/gcc-riscv64-unknown-elf-10.2.0=. -fstack-protector-strong' CPPFLAGS='-Wdate-time -D_FORTIFY_SOURCE=2' CXXFLAGS='-g -O2 -fdebug-prefix-map=/build/gcc-riscv64-unknown-elf-LkcieF/gcc-riscv64-unknown-elf-10.2.0=. -fstack-protector-strong' FCFLAGS='-g -O2 -fdebug-prefix-map=/build/gcc-riscv64-unknown-elf-LkcieF/gcc-riscv64-unknown-elf-10.2.0=. -fstack-protector-strong' FFLAGS='-g -O2 -fdebug-prefix-map=/build/gcc-riscv64-unknown-elf-LkcieF/gcc-riscv64-unknown-elf-10.2.0=. -fstack-protector-strong' GCJFLAGS='-g -O2 -fdebug-prefix-map=/build/gcc-riscv64-unknown-elf-LkcieF/gcc-riscv64-unknown-elf-10.2.0=. -fstack-protector-strong' LDFLAGS='-Wl,-Bsymbolic-functions -Wl,-z,relro -Wl,-z,now' OBJCFLAGS='-g -O2 -fdebug-prefix-map=/build/gcc-riscv64-unknown-elf-LkcieF/gcc-riscv64-unknown-elf-10.2.0=. -fstack-protector-strong' OBJCXXFLAGS='-g -O2 -fdebug-prefix-map=/build/gcc-riscv64-unknown-elf-LkcieF/gcc-riscv64-unknown-elf-10.2.0=. -fstack-protector-strong' 'CFLAGS_FOR_TARGET=-Os -mcmodel=medany' 'CXXFLAGS_FOR_TARGET=-Os -mcmodel=medany'
Thread model: single
Supported LTO compression algorithms: zlib
gcc version 10.2.0 ()

[pkarashchenko]

This is a know issue. Ubuntu release of RISC-V GCC is compiled without math libs. We can do nothing with that, but you can enable NuttX native math libraries support via CONFIG_ LIBM=y and still use RISC-V GCC provided by Ubuntu apt or pick another more mature toolchain

[pkarashchenko]

Closing this. Please re-open if needed.

[yf13]

@pkarashchenko thanks! I wasn't able to find an explanation in historical issues or documents, thus raised it here.
Just confirmed that CONFIG_LIBM works well.

[pkarashchenko]

Yeah, it is not in docs since we are not managing tools created externally, but there was some discussion in one of the PRs