Doesn't compile for `x86_64-fortanix-unknown-sgx` on newer distros

[DragonDev1906]

When building mbedtls for the x86_64-fortanix-unknown-sgx target on newer linux distros (e.g. Arch or debian testing) you get the following error:

Note that the compilation does not fail because of the cmake version but somewhere related to /usr/include/bits/floatn.h. Compilation worked on previous arch versions when setting the CMAKE_POLICY_VERSION_MINIMUM=3.5 environment variable.

cargo build --target x86_64-fortanix-unknown-sgx

  --- stderr
  CMake Deprecation Warning at CMakeLists.txt:23 (cmake_minimum_required):
    Compatibility with CMake < 3.10 will be removed from a future version of
    CMake.

    Update the VERSION argument <min> value.  Or, use the <min>...<max> syntax
    to tell CMake that the project requires at least <min> but has been updated
    to work with policies introduced by <max> or earlier.


  System is unknown to cmake, create:
  Platform/unknown to use this system, please post your config file on discourse.cmake.org so it can be added to cmake
  System is unknown to cmake, create:
  Platform/unknown to use this system, please post your config file on discourse.cmake.org so it can be added to cmake
  System is unknown to cmake, create:
  Platform/unknown to use this system, please post your config file on discourse.cmake.org so it can be added to cmake
  CMake Warning:
    Manually-specified variables were not used by the project:

      CMAKE_ASM_COMPILER
      CMAKE_ASM_FLAGS
      CMAKE_CXX_COMPILER
      CMAKE_CXX_FLAGS
      GEN_FILES


  error: version 'sgx' in target triple 'x86_64-fortanix-unknown-sgx' is invalid
  /usr/include/bits/floatn.h:83:52: error: unsupported machine mode '__TC__'
  /usr/include/bits/floatn.h:97:9: error: __float128 is not supported on this target

  thread 'main' panicked at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/mbedtls-sys-auto-2.28.11/build/bindgen.rs:151:14:
  bindgen error: ClangDiagnostic("error: version 'sgx' in target triple 'x86_64-fortanix-unknown-sgx' is invalid\n/usr/include/bits/floatn.h:83:52: error: unsupported machine mode '__TC__'\n/usr/include/bits/floatn.h:97:9: error: __float128 is not supported on this target\n")

SGX (probably) isn't (officially) supported on these distros, but it is still useful to be able to run cargo build or cargo check on them.

How to reproduce

For reproducibility (at least to some extend) I've tested compilation in docker, using the commands shown below.

Compilation fails with the error above

# docker run -it archlinux
CMAKE_POLICY_VERSION_MINIMUM=3.10 pacman -Sy rustup make cmake clang && rustup default stable && rustup target add x86_64-fortanix-unknown-sgx && cargo new app && cd app && cargo add mbedtls && cargo build --target x86_64-fortanix-unknown-sgx

# docker run -it debian:testing
apt update && apt install curl cmake clang gcc-multilib && curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh && . "$HOME/.cargo/env" && rustup default stable && rustup target add x86_64-fortanix-unknown-sgx && cargo new app && cd app && cargo add mbedtls && cargo build --target x86_64-fortanix-unknown-sgx

Note that CMAKE_POLICY_VERSION_MINIMUM=3.10 seems to be required on archlinux because cmake isn't old enough.

Compiling in these distros/images works

# docker run -it rust
apt update && apt install cmake clang gcc-multilib && rustup target add x86_64-fortanix-unknown-sgx  && cargo new app && cd app && cargo add mbedtls && cargo build --target x86_64-fortanix-unknown-sgx

# docker run -it debian
apt update && apt install curl cmake clang gcc-multilib && curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh && . "$HOME/.cargo/env" && rustup default stable && rustup target add x86_64-fortanix-unknown-sgx && cargo new app && cd app && cargo add mbedtls && cargo build --target x86_64-fortanix-unknown-sgx

[jethrogb]

Are you setting CFLAGS like so?

[DragonDev1906]

I did not during testing (none of these where set except for CMAKE_POLICY_VERSION_MINIMUM), but when adding them I get the same error (though printed a multiple times in a different format):

CFLAGS_x86_64_fortanix_unknown_sgx="-isystem/usr/include/x86_64-linux-gnu -mlvi-hardening -mllvm -x86-experimental-lvi-inline-asm-hardening" \
CC_x86_64_fortanix_unknown_sgx=/usr/lib/llvm18/bin/clang-18 \
CC_aarch64_unknown_linux_musl=/usr/bin/musl-gcc \
CMAKE_POLICY_VERSION_MINIMUM=3.5 \
cargo build --target x86_64-fortanix-unknown-sgx -p mbedtls

  --- stderr
  CMake Deprecation Warning at CMakeLists.txt:23 (cmake_minimum_required):
    Compatibility with CMake < 3.10 will be removed from a future version of
    CMake.

    Update the VERSION argument <min> value.  Or, use the <min>...<max> syntax
    to tell CMake that the project requires at least <min> but has been updated
    to work with policies introduced by <max> or earlier.


  System is unknown to cmake, create:
  Platform/unknown to use this system, please post your config file on discourse.cmake.org so it can be added to cmake
  Your CMakeCache.txt file was copied to CopyOfCMakeCache.txt. Please post that file on discourse.cmake.org.
  In file included from /home/jens/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/mbedtls-sys-auto-2.28.10/vendor/library/aes.c:21:
  In file included from /home/jens/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/mbedtls-sys-auto-2.28.10/vendor/include/mbedtls/platform.h:66:
  In file included from /usr/include/stdio.h:437:
  /usr/include/bits/floatn.h:83:52: error: unsupported machine mode '__TC__'
     83 | typedef _Complex float __cfloat128 __attribute__ ((__mode__ (__TC__)));
        |                                                    ^
  /usr/include/bits/floatn.h:97:9: error: __float128 is not supported on this target
     97 | typedef __float128 _Float128;
        |         ^
  2 errors generated.
  make[2]: *** [library/CMakeFiles/mbedcrypto.dir/build.make:79: library/CMakeFiles/mbedcrypto.dir/aes.c.obj] Error 1
  make[1]: *** [CMakeFiles/Makefile2:234: library/CMakeFiles/mbedcrypto.dir/all] Error 2
  make: *** [Makefile:136: all] Error 2

  thread 'main' panicked at /home/jens/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/cmake-0.1.54/src/lib.rs:1119:5:

  command did not execute successfully, got: exit status: 2

  build script failed, must exit now
  note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
warning: build failed, waiting for other jobs to finish...
warning: rs-libc@0.2.4: In file included from src/c/floatscan.c:3:
warning: rs-libc@0.2.4: In file included from /usr/include/math.h:43:
warning: rs-libc@0.2.4: /usr/include/bits/floatn.h:83:52: error: unsupported machine mode '__TC__'
warning: rs-libc@0.2.4:    83 | typedef _Complex float __cfloat128 __attribute__ ((__mode__ (__TC__)));
warning: rs-libc@0.2.4:       |                                                    ^
warning: rs-libc@0.2.4: /usr/include/bits/floatn.h:97:9: error: __float128 is not supported on this target
warning: rs-libc@0.2.4:    97 | typedef __float128 _Float128;
warning: rs-libc@0.2.4:       |         ^
warning: rs-libc@0.2.4: 2 errors generated.
warning: rs-libc@0.2.4: ToolExecError: command did not execute successfully (status code exit status: 1): LC_ALL="C" "/usr/lib/llvm18/bin/clang-18" "-O0" "-ffunction-sections" "-fdata-sections" "-fPIC" "-g" "-fno-omit-frame-pointer" "-m64" "--target=x86_64-elf" "-U_FORTIFY_SOURCE" "-ffreestanding" "-Dweak_alias(old,new)=extern __typeof(old) new __attribute__((alias(#old)))" "-D_FORTIFY_SOURCE=0" "-D__NO_STRING_INLINES" "-D__NO_MATH_INLINES" "-isystem/usr/include/x86_64-linux-gnu" "-mlvi-hardening" "-mllvm" "-x86-experimental-lvi-inline-asm-hardening" "-o" "/home/jens/git/erdstall-mono/target/x86_64-fortanix-unknown-sgx/debug/build/rs-libc-12d5cbd94d19216b/out/01f2103c15c31950-floatscan.o" "-c" "src/c/floatscan.c"
warning: rs-libc@0.2.4: In file included from src/c/strdup.c:1:
warning: rs-libc@0.2.4: In file included from /usr/include/stdlib.h:56:
warning: rs-libc@0.2.4: /usr/include/bits/floatn.h:83:52: error: unsupported machine mode '__TC__'
warning: rs-libc@0.2.4:    83 | typedef _Complex float __cfloat128 __attribute__ ((__mode__ (__TC__)));
warning: rs-libc@0.2.4:       |                                                    ^
warning: rs-libc@0.2.4: /usr/include/bits/floatn.h:97:9: error: __float128 is not supported on this target
warning: rs-libc@0.2.4:    97 | typedef __float128 _Float128;
warning: rs-libc@0.2.4:       |         ^
warning: rs-libc@0.2.4: 2 errors generated.
warning: rs-libc@0.2.4: ToolExecError: command did not execute successfully (status code exit status: 1): LC_ALL="C" "/usr/lib/llvm18/bin/clang-18" "-O0" "-ffunction-sections" "-fdata-sections" "-fPIC" "-g" "-fno-omit-frame-pointer" "-m64" "--target=x86_64-elf" "-U_FORTIFY_SOURCE" "-ffreestanding" "-Dweak_alias(old,new)=extern __typeof(old) new __attribute__((alias(#old)))" "-D_FORTIFY_SOURCE=0" "-D__NO_STRING_INLINES" "-D__NO_MATH_INLINES" "-isystem/usr/include/x86_64-linux-gnu" "-mlvi-hardening" "-mllvm" "-x86-experimental-lvi-inline-asm-hardening" "-o" "/home/jens/git/erdstall-mono/target/x86_64-fortanix-unknown-sgx/debug/build/rs-libc-12d5cbd94d19216b/out/01f2103c15c31950-strdup.o" "-c" "src/c/strdup.c"cargo:warning=In file included from src/c/strtod.c:1:
warning: rs-libc@0.2.4: In file included from /usr/include/stdlib.h:56:
warning: rs-libc@0.2.4: /usr/include/bits/floatn.h:83:52: error: unsupported machine mode '__TC__'
warning: rs-libc@0.2.4:    83 | typedef _Complex float __cfloat128 __attribute__ ((__mode__ (__TC__)));
warning: rs-libc@0.2.4:       |                                                    ^
warning: rs-libc@0.2.4: /usr/include/bits/floatn.h:97:9: error: __float128 is not supported on this target
warning: rs-libc@0.2.4:    97 | typedef __float128 _Float128;
warning: rs-libc@0.2.4:       |         ^
warning: rs-libc@0.2.4: 2 errors generated.
warning: rs-libc@0.2.4: ToolExecError: command did not execute successfully (status code exit status: 1): LC_ALL="C" "/usr/lib/llvm18/bin/clang-18" "-O0" "-ffunction-sections" "-fdata-sections" "-fPIC" "-g" "-fno-omit-frame-pointer" "-m64" "--target=x86_64-elf" "-U_FORTIFY_SOURCE" "-ffreestanding" "-Dweak_alias(old,new)=extern __typeof(old) new __attribute__((alias(#old)))" "-D_FORTIFY_SOURCE=0" "-D__NO_STRING_INLINES" "-D__NO_MATH_INLINES" "-isystem/usr/include/x86_64-linux-gnu" "-mlvi-hardening" "-mllvm" "-x86-experimental-lvi-inline-asm-hardening" "-o" "/home/jens/git/erdstall-mono/target/x86_64-fortanix-unknown-sgx/debug/build/rs-libc-12d5cbd94d19216b/out/01f2103c15c31950-strtod.o" "-c" "src/c/strtod.c"
error: failed to run custom build command for `rs-libc v0.2.4`

Caused by:
  process didn't exit successfully: `/home/jens/git/erdstall-mono/target/debug/build/rs-libc-c61ae4fa9c8c5511/build-script-build` (exit status: 1)
  --- stdout
  OUT_DIR = Some(/home/jens/git/erdstall-mono/target/x86_64-fortanix-unknown-sgx/debug/build/rs-libc-12d5cbd94d19216b/out)
  OPT_LEVEL = Some(0)
  TARGET = Some(x86_64-fortanix-unknown-sgx)
  HOST = Some(x86_64-unknown-linux-gnu)
  cargo:rerun-if-env-changed=CC_x86_64-fortanix-unknown-sgx
  CC_x86_64-fortanix-unknown-sgx = None
  cargo:rerun-if-env-changed=CC_x86_64_fortanix_unknown_sgx
  CC_x86_64_fortanix_unknown_sgx = Some(/usr/lib/llvm18/bin/clang-18)
  RUSTC_WRAPPER = None
  cargo:rerun-if-env-changed=CC_ENABLE_DEBUG_OUTPUT
  cargo:rerun-if-env-changed=CRATE_CC_NO_DEFAULTS
  CRATE_CC_NO_DEFAULTS = None
  DEBUG = Some(true)
  cargo:rerun-if-env-changed=CFLAGS
  CFLAGS = None
  cargo:rerun-if-env-changed=TARGET_CFLAGS
  TARGET_CFLAGS = None
  cargo:rerun-if-env-changed=CFLAGS_x86_64_fortanix_unknown_sgx
  CFLAGS_x86_64_fortanix_unknown_sgx = Some(-isystem/usr/include/x86_64-linux-gnu -mlvi-hardening -mllvm -x86-experimental-lvi-inline-asm-hardening)
  cargo:rerun-if-env-changed=CC_SHELL_ESCAPED_FLAGS
  CC_SHELL_ESCAPED_FLAGS = None
  cargo:rerun-if-env-changed=CFLAGS_x86_64-fortanix-unknown-sgx
  CFLAGS_x86_64-fortanix-unknown-sgx = None
  CARGO_ENCODED_RUSTFLAGS = Some()
  exit status: 0
  exit status: 0
  exit status: 0
  exit status: 0
  exit status: 0
  exit status: 0
  exit status: 0
  exit status: 0
  cargo:warning=In file included from src/c/floatscan.c:3:
  cargo:warning=In file included from /usr/include/math.h:43:
  cargo:warning=/usr/include/bits/floatn.h:83:52: error: unsupported machine mode '__TC__'
  cargo:warning=   83 | typedef _Complex float __cfloat128 __attribute__ ((__mode__ (__TC__)));
  cargo:warning=      |                                                    ^
  cargo:warning=/usr/include/bits/floatn.h:97:9: error: __float128 is not supported on this target
  cargo:warning=   97 | typedef __float128 _Float128;
  cargo:warning=      |         ^
  cargo:warning=2 errors generated.
  exit status: 0
  exit status: 0
  exit status: 0
  exit status: 0
  exit status: 0
  exit status: 0
  exit status: 0
  exit status: 0
  exit status: 1
  cargo:warning=ToolExecError: command did not execute successfully (status code exit status: 1): LC_ALL="C" "/usr/lib/llvm18/bin/clang-18" "-O0" "-ffunction-sections" "-fdata-sections" "-fPIC" "-g" "-fno-omit-frame-pointer" "-m64" "--target=x86_64-elf" "-U_FORTIFY_SOURCE" "-ffreestanding" "-Dweak_alias(old,new)=extern __typeof(old) new __attribute__((alias(#old)))" "-D_FORTIFY_SOURCE=0" "-D__NO_STRING_INLINES" "-D__NO_MATH_INLINES" "-isystem/usr/include/x86_64-linux-gnu" "-mlvi-hardening" "-mllvm" "-x86-experimental-lvi-inline-asm-hardening" "-o" "/home/jens/git/erdstall-mono/target/x86_64-fortanix-unknown-sgx/debug/build/rs-libc-12d5cbd94d19216b/out/01f2103c15c31950-floatscan.o" "-c" "src/c/floatscan.c"
  exit status: 0
  exit status: 0
  exit status: 0
  exit status: 0
  exit status: 0
  exit status: 0
  exit status: 0
  exit status: 0
  cargo:warning=In file included from src/c/strdup.c:1:
  cargo:warning=In file included from /usr/include/stdlib.h:56:
  cargo:warning=/usr/include/bits/floatn.h:83:52: error: unsupported machine mode '__TC__'
  cargo:warning=   83 | typedef _Complex float __cfloat128 __attribute__ ((__mode__ (__TC__)));
  cargo:warning=      |                                                    ^
  cargo:warning=/usr/include/bits/floatn.h:97:9: error: __float128 is not supported on this target
  cargo:warning=   97 | typedef __float128 _Float128;
  cargo:warning=      |         ^
  cargo:warning=2 errors generated.
  exit status: 0
  exit status: 0
  exit status: 0
  exit status: 1
  cargo:warning=ToolExecError: command did not execute successfully (status code exit status: 1): LC_ALL="C" "/usr/lib/llvm18/bin/clang-18" "-O0" "-ffunction-sections" "-fdata-sections" "-fPIC" "-g" "-fno-omit-frame-pointer" "-m64" "--target=x86_64-elf" "-U_FORTIFY_SOURCE" "-ffreestanding" "-Dweak_alias(old,new)=extern __typeof(old) new __attribute__((alias(#old)))" "-D_FORTIFY_SOURCE=0" "-D__NO_STRING_INLINES" "-D__NO_MATH_INLINES" "-isystem/usr/include/x86_64-linux-gnu" "-mlvi-hardening" "-mllvm" "-x86-experimental-lvi-inline-asm-hardening" "-o" "/home/jens/git/erdstall-mono/target/x86_64-fortanix-unknown-sgx/debug/build/rs-libc-12d5cbd94d19216b/out/01f2103c15c31950-strdup.o" "-c" "src/c/strdup.c"cargo:warning=In file included from src/c/strtod.c:1:
  cargo:warning=In file included from /usr/include/stdlib.h:56:
  cargo:warning=/usr/include/bits/floatn.h:83:52: error: unsupported machine mode '__TC__'
  cargo:warning=   83 | typedef _Complex float __cfloat128 __attribute__ ((__mode__ (__TC__)));
  cargo:warning=      |                                                    ^
  cargo:warning=/usr/include/bits/floatn.h:97:9: error: __float128 is not supported on this target
  cargo:warning=   97 | typedef __float128 _Float128;
  cargo:warning=      |         ^
  cargo:warning=2 errors generated.

  exit status: 0
  exit status: 0
  exit status: 0
  exit status: 0
  exit status: 0
  exit status: 0
  exit status: 0
  exit status: 1
  cargo:warning=ToolExecError: command did not execute successfully (status code exit status: 1): LC_ALL="C" "/usr/lib/llvm18/bin/clang-18" "-O0" "-ffunction-sections" "-fdata-sections" "-fPIC" "-g" "-fno-omit-frame-pointer" "-m64" "--target=x86_64-elf" "-U_FORTIFY_SOURCE" "-ffreestanding" "-Dweak_alias(old,new)=extern __typeof(old) new __attribute__((alias(#old)))" "-D_FORTIFY_SOURCE=0" "-D__NO_STRING_INLINES" "-D__NO_MATH_INLINES" "-isystem/usr/include/x86_64-linux-gnu" "-mlvi-hardening" "-mllvm" "-x86-experimental-lvi-inline-asm-hardening" "-o" "/home/jens/git/erdstall-mono/target/x86_64-fortanix-unknown-sgx/debug/build/rs-libc-12d5cbd94d19216b/out/01f2103c15c31950-strtod.o" "-c" "src/c/strtod.c"
  exit status: 0

  --- stderr


  error occurred in cc-rs: command did not execute successfully (status code exit status: 1): LC_ALL="C" "/usr/lib/llvm18/bin/clang-18" "-O0" "-ffunction-sections" "-fdata-sections" "-fPIC" "-g" "-fno-omit-frame-pointer" "-m64" "--target=x86_64-elf" "-U_FORTIFY_SOURCE" "-ffreestanding" "-Dweak_alias(old,new)=extern __typeof(old) new __attribute__((alias(#old)))" "-D_FORTIFY_SOURCE=0" "-D__NO_STRING_INLINES" "-D__NO_MATH_INLINES" "-isystem/usr/include/x86_64-linux-gnu" "-mlvi-hardening" "-mllvm" "-x86-experimental-lvi-inline-asm-hardening" "-o" "/home/jens/git/erdstall-mono/target/x86_64-fortanix-unknown-sgx/debug/build/rs-libc-12d5cbd94d19216b/out/01f2103c15c31950-strtod.o" "-c" "src/c/strtod.c"

Though I'm not sure if musl-gcc from the musl package (Arch) is the right one for CC_aarch64_unknown_linux_musl.

[jethrogb]

x86_64-fortanix-unknown-sgx doesn't have a libc, so it also doesn't have the standard C headers, and it doesn't have a defined target for C compilers. W.r.t. the C headers, we used to kind of hack it by using the GNU libc headers installed on the system, which "just worked" because the environments were similar enough. And for the target triple, the C compilers used to be able to handle it well enough. It seems like newer versions of libc as well as the C compiler have broken this. To resolve all this, new workarounds will need to be found.

We internally use Ubuntu 24.04 and I don't think we'll be able to spend time on this issue soon.

[DragonDev1906]

I assume there are no good ways around this or alternatives to mbedtls (esp. considering that dcap-ql depends directly on it), correct?

What is the plan when 24.04 goes EOL (yes, that'll be a while until then)? I have not tested if it works on 25.04.

Thank you for the quick response.

[jethrogb]

Haven't though about a plan yet for 2029 😅

[jethrogb]

We'll likely want to keep supporting some kind of C code compilation for the foreseeable future.