Add initial armv7 support

cmake/toolchain/armv7a-gcc

@@ -0,0 +1,20 @@
+set(CMAKE_SYSTEM_NAME Linux)
+set(TOOLCHAIN_PREFIX armv7a-unknown-linux-gnueabihf)
+
+set(CMAKE_C_COMPILER ${TOOLCHAIN_PREFIX}-gcc)
+set(CMAKE_CXX_COMPILER ${TOOLCHAIN_PREFIX}-g++)
+
+set(CMAKE_FIND_ROOT_PATH "/usr/${TOOLCHAIN_PREFIX};/usr/lib/gcc/${TOOLCHAIN_PREFIX}/;${CMAKE_CURRENT_BINARY_DIR}/deps")
+
+# modify default behavior of FIND_XXX() commands to
+# search for headers/libs in the target environment and
+# search for programs in the build host environment
+set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
+set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
+
+# Export the chosen compiler via CXX and CC, because it's entirely possible
+# one of child build scripts will call out to something that relies on these
+# to discover the compiler (or will otherwise choose the wrong one).
+set ($ENV{CXX} "${CMAKE_CXX_COMPILER}")
+set ($ENV{CC} "${CMAKE_C_COMPILER}")

conan/profile/armv7-gcc-linux-release

@@ -0,0 +1,23 @@
+toolchain=/usr/armv7a-unknown-linux-gnueabihf
+target_host=armv7a-unknown-linux-gnueabihf
+cc_compiler=gcc
+cxx_compiler=g++
+
+[env]
+CONAN_CMAKE_FIND_ROOT_PATH=$toolchain
+CHOST=$target_host
+AR=$target_host-ar
+AS=$target_host-as
+RANLIB=$target_host-ranlib
+CC=$target_host-$cc_compiler
+CXX=$target_host-$cxx_compiler
+STRIP=$target_host-strip
+
+[settings]
+os=Linux
+arch=armv7
+compiler=gcc
+
+compiler.version=10.2
+compiler.libcxx=libstdc++11
+build_type=Release

init.py

@@ -152,6 +152,20 @@ OPTIONS['mingw'] = Option(
 )
 
 
+# -----------------------------------------------------------------------------
+OPTIONS['pi3'] = Option(
+    vars={
+        'CMAKE_TOOLCHAIN_FILE': os.path.join(
+            os.path.dirname(__file__),
+            'cmake', 'toolchain', 'armv7a-gcc'
+        )
+    },
+    arch="armv7",
+    compiler='gcc',
+    platform='linux',
+)
+
+
 # -----------------------------------------------------------------------------
 DEFAULT_OPTION = Option(
     vars={
@@ -213,6 +227,7 @@ if __name__ == '__main__':
 
     accumulated = [f'"-D{key}={val}"' for key, val in accum.vars.items()] + accum.args
 
+    conan_build_profile = 'x86_64-gcc-linux-release'
     conan_host_profile = '-'.join([
         accum.arch,
         accum.compiler,
@@ -220,7 +235,6 @@ if __name__ == '__main__':
         accum.config,
     ])
 
-    conan_build_profile = conan_host_profile
     if accum.platform == 'mingw':
         conan_build_profile = f'x86_64-gcc-linux-{accum.config}'