Fix CMake detection of cross-compilers on arm/arm64 build arch #35084

basilgello · 2023-11-13T14:00:43Z

Fixes cross-building arm-linux / arm64-linux hon non-x86_64 hosts

Signed-off-by: Vasyl Gello <vasek.gello@gmail.com>

basilgello · 2023-11-13T14:03:54Z

Rustdesk is built not only on amd64 hosts but aarch64 builders. CMake detects Debian/Ubuntu cross-compilers only for x86_64 architecture. With this patch, aarch64 builders produce arm-linux builds.

basilgello · 2023-11-16T04:48:14Z

@dg0yt please have a look here :)

basilgello · 2023-11-20T14:44:38Z

@dg0yt @data-queue :)

dg0yt · 2023-11-20T18:30:30Z

Is the use of prefixed tool names the common solution to target arm from arm64?

From a more general perspective, the toolchain should probably look for <gnu-triplet>-gcc etc. when the variable isn't set and the target cpu doesn't match the host cpu (at least in more significant regards than-m32/-m64 bitness).
But I'm not an expert in this field.

basilgello · 2023-11-20T18:48:05Z

Is the prefixed tool names the common solution to target arm from arm64 ?

Yes, and that's not only in Debian (where I test it all). Unfortunately -m32 / -m64 is x86 specific - other architectures in GCC have this convention.

Clang is different - see --target

BillyONeal · 2023-11-22T04:21:08Z

scripts/toolchains/linux.cmake

@@ -13,7 +13,7 @@ elseif(VCPKG_TARGET_ARCHITECTURE STREQUAL "x86")
 string(APPEND VCPKG_LINKER_FLAGS " -m32")
 elseif(VCPKG_TARGET_ARCHITECTURE STREQUAL "arm")
 set(CMAKE_SYSTEM_PROCESSOR armv7l CACHE STRING "")
- if(CMAKE_HOST_SYSTEM_NAME STREQUAL "Linux" AND CMAKE_HOST_SYSTEM_PROCESSOR STREQUAL "x86_64")
+ if(CMAKE_HOST_SYSTEM_NAME STREQUAL "Linux")


Removing the test entirely seems wrong as that will do the wrong thing when arm is the native architecture?

Wrong, yes. But not worse than current support for modern arm64 hosts.
How much of vcpkg works out of the box on 32-bit arm hosts? The user must provide cmake and ninja, so maybe it is fair to ask for providing the compiler variables, too.

Couldn't we do find_program(var NAMES <prefix>-tool tool ...) ? This would consider user input, prefix, default. Hard-coded values belong into custom toolchain files.

Should I declare the table of possible combinations of host & target instead?

Couldn't we do find_program(var NAMES <prefix>-tool tool ...) ? This would consider user input, prefix, default. Hard-coded values belong into custom toolchain files.

FTR find_program is what scripts/cmake/mingw.cmake does:

vcpkg/scripts/toolchains/mingw.cmake

Lines 24 to 25 in 23ceb9c

find_program(CMAKE_C_COMPILER "${CMAKE_SYSTEM_PROCESSOR}-w64-mingw32-gcc")

find_program(CMAKE_CXX_COMPILER "${CMAKE_SYSTEM_PROCESSOR}-w64-mingw32-g++")

(However, I noticed this now due to insufficient initalization of CMAKE_SYSTEM_PROCESSOR in a test project.)

Wrong, yes. But not worse than current support for modern arm64 hosts.

OK, I'm sold by 'not worse than the status quo'

The user must provide cmake and ninja, so maybe it is fair to ask for providing the compiler variables, too.

Sadly that doesn't seem to be so easy, overriding the variables from the command-line doesn't work... maybe via a triplet, but that would introduce a fair bit of hassle for anyone who wants to perform a native build on an ARM machine. Ideally, we should just make the defaults work (see my comment below and #38113).

Ideally, we should just make the defaults work

Yes, we can agree on that, and #38113 is a good direction. It is just not the whole discussion from the last days.

BillyONeal · 2023-12-05T00:46:22Z

Thanks!

fwcd · 2024-04-10T16:48:24Z

Wrong, yes. But not worse than current support for modern arm64 hosts.

Unfortunately, this did actually break things. Most arm64 Linux hosts report as aarch64, causing vcpkg to think that it cross-compiles, which then results in very obscure errors such as:

error: while detecting compiler information:
The log file content at "/home/<user>/git/vcpkg/buildtrees/detect_compiler/stdout-arm64-linux.log" is:
-- Configuring arm64-linux-rel
CMake Error at scripts/cmake/vcpkg_execute_required_process.cmake:112 (message):
    Command failed: /usr/bin/cmake /home/<user>/git/vcpkg/scripts/detect_compiler -G Ninja -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=/home/<user>/git/vcpkg/packages/detect_compiler_arm64-linux -DCMAKE_SYSTEM_NAME=Linux -DBUILD_SHARED_LIBS=OFF -DVCPKG_CHAINLOAD_TOOLCHAIN_FILE=/home/<user>/git/vcpkg/scripts/toolchains/linux.cmake -DVCPKG_TARGET_TRIPLET=arm64-linux -DVCPKG_SET_CHARSET_FLAG=ON -DVCPKG_PLATFORM_TOOLSET=external -DCMAKE_EXPORT_NO_PACKAGE_REGISTRY=ON -DCMAKE_FIND_PACKAGE_NO_PACKAGE_REGISTRY=ON -DCMAKE_FIND_PACKAGE_NO_SYSTEM_PACKAGE_REGISTRY=ON -DCMAKE_INSTALL_SYSTEM_RUNTIME_LIBS_SKIP=TRUE -DCMAKE_VERBOSE_MAKEFILE=ON -DVCPKG_APPLOCAL_DEPS=OFF -DCMAKE_TOOLCHAIN_FILE=/home/<user>/git/vcpkg/scripts/buildsystems/vcpkg.cmake -DCMAKE_ERROR_ON_ABSOLUTE_INSTALL_DESTINATION=ON -DVCPKG_CXX_FLAGS= -DVCPKG_CXX_FLAGS_RELEASE= -DVCPKG_CXX_FLAGS_DEBUG= -DVCPKG_C_FLAGS= -DVCPKG_C_FLAGS_RELEASE= -DVCPKG_C_FLAGS_DEBUG= -DVCPKG_CRT_LINKAGE=dynamic -DVCPKG_LINKER_FLAGS= -DVCPKG_LINKER_FLAGS_RELEASE= -DVCPKG_LINKER_FLAGS_DEBUG= -DVCPKG_TARGET_ARCHITECTURE=arm64 -DCMAKE_INSTALL_LIBDIR:STRING=lib -DCMAKE_INSTALL_BINDIR:STRING=bin -D_VCPKG_ROOT_DIR=/home/<user>/git/vcpkg -DZ_VCPKG_ROOT_DIR=/home/<user>/git/vcpkg -D_VCPKG_INSTALLED_DIR=/home/<user>/git/vcpkg/installed -DVCPKG_MANIFEST_INSTALL=OFF
    Working Directory: /home/<user>/git/vcpkg/buildtrees/detect_compiler/arm64-linux-rel
    Error code: 1
    See logs for more information:
      /home/<user>/git/vcpkg/buildtrees/detect_compiler/config-arm64-linux-rel-CMakeCache.txt.log
      /home/<user>/git/vcpkg/buildtrees/detect_compiler/config-arm64-linux-rel-out.log
      /home/<user>/git/vcpkg/buildtrees/detect_compiler/config-arm64-linux-rel-err.log

Call Stack (most recent call first):
  scripts/cmake/vcpkg_configure_cmake.cmake:344 (vcpkg_execute_required_process)
  scripts/detect_compiler/portfile.cmake:18 (vcpkg_configure_cmake)
  scripts/ports.cmake:175 (include)


error: vcpkg was unable to detect the active compiler's information. See above for the CMake failure output.

with config-arm64-linux-rel-out.log:

-- Cross compiling arm64 on host aarch64, use cross compiler: aarch64-linux-gnu-g++/aarch64-linux-gnu-gcc
-- The C compiler identification is unknown
-- Configuring incomplete, errors occurred!

with config-arm64-linux-rel-err.log:

CMake Error at CMakeLists.txt:11 (enable_language):
  The CMAKE_C_COMPILER:

    aarch64-linux-gnu-gcc

  is not a full path and was not found in the PATH.

  Tell CMake where to find the compiler by setting either the environment
  variable "CC" or the CMake cache entry CMAKE_C_COMPILER to the full path to
  the compiler, or to the compiler name if it is in the PATH.

From my experimentation, the issue can be solved either

by making sure we don't try to reference a cross-compiler if we don't cross-compile
by using aarch64 instead of arm64 in the triplet (though having multiple arm64 triplets would probably only cause confusion)

#35084 introduced a regression for native ARM Linux builds where the toolchain would mistakenly try to reference a cross-compiler (e.g. `aarch64-linux-gnu-gcc`) despite building natively because vcpkg spells the architecture differently from what the system reports (`arm64` vs. `aarch64`). This fixes the issue by checking whether the `CMAKE_HOST_SYSTEM_PROCESSOR` matches the target (in CMake's spelling of the architecture). --------- Co-authored-by: Kai Pastor <dg0yt@darc.de>

Fix CMake detection of cross-compilers on arm/arm64 build arch

f1f05c7

Signed-off-by: Vasyl Gello <vasek.gello@gmail.com>

Cheney-W assigned LilyWangLL Nov 14, 2023

LilyWangLL added the category:tool-update The issue is with build tool or build script, which requires update or should be executed correctly label Nov 14, 2023

LilyWangLL approved these changes Nov 21, 2023

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LilyWangLL added the info:reviewed Pull Request changes follow basic guidelines label Nov 21, 2023

data-queue added the requires:vcpkg-team-review This PR or issue requires someone on the vcpkg team to take a further look. label Nov 22, 2023

BillyONeal reviewed Nov 22, 2023

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BillyONeal merged commit aa628ce into microsoft:master Dec 5, 2023
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trolgar mentioned this pull request Dec 16, 2023

[libcap] Build error on arm-linux #35661

Closed

scareything mentioned this pull request Jan 9, 2024

update vcpkg baseline to 2023.12.12 openziti/ziti-sdk-c#612

Merged

azolotko mentioned this pull request Feb 8, 2024

[arrow] 14.0.2 unable to detect the active compiler's information #36094

Open

fwcd mentioned this pull request Apr 10, 2024

[linux] Fix compiler in native ARM host builds #38113

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Fix CMake detection of cross-compilers on arm/arm64 build arch #35084

Fix CMake detection of cross-compilers on arm/arm64 build arch #35084

basilgello commented Nov 13, 2023

basilgello commented Nov 13, 2023

basilgello commented Nov 16, 2023

basilgello commented Nov 20, 2023

dg0yt commented Nov 20, 2023

basilgello commented Nov 20, 2023 •

edited

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BillyONeal Nov 22, 2023

dg0yt Nov 22, 2023

basilgello Nov 22, 2023

dg0yt Nov 23, 2023

BillyONeal Dec 5, 2023

fwcd Apr 10, 2024

dg0yt Apr 10, 2024

BillyONeal commented Dec 5, 2023

fwcd commented Apr 10, 2024

	find_program(CMAKE_C_COMPILER "${CMAKE_SYSTEM_PROCESSOR}-w64-mingw32-gcc")
	find_program(CMAKE_CXX_COMPILER "${CMAKE_SYSTEM_PROCESSOR}-w64-mingw32-g++")

Fix CMake detection of cross-compilers on arm/arm64 build arch #35084

Fix CMake detection of cross-compilers on arm/arm64 build arch #35084

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basilgello commented Nov 13, 2023

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