I am seeing the following error when cross-compiling go source on ARM with
-buildmode=pie. Despite the error (or is it a warning?), the compilation
succeeds
(i.e. go build exits with 0 and the binary is created). Adding CGO_ENABLED=1
(since this is cross-compilation, cgo is disabled by default) eliminates
the warning.
Please see a complete repro below. This happens on the following linux
platforms:
- armel aka arm v6;
- armhf aka arm v7;
- riscv64;
- s390x.
It does NOT happen
- natively (linux/amd64);
- on arm64.
- on ppc64le.
I haven't tried anything else (e.g. mips or 386), nor have I checked that
the resulting binaries work.
My questions are:
1. If "loadinternal: cannot find runtime/cgo" is an error, why go build
creates the binary and exits with code of 0? This looks like a bug.
2. Does -buildmode=pie require enabling cgo?
Here's a repro using docker or podman (I guess you can do the same without
Docker on a Debian machine).
--------
mkdir hello
cd hello
# Create the Dockerfile.
cat << _EOF_ > Dockerfile
FROM golang:1.18.0-bullseye
RUN apt-get -qq update \
&& apt-get -qq -y install gcc-arm-linux-gnueabi libc-dev-armel-cross
ENV HOST=arm-linux-gnueabi GOARCH=arm GOARM=6 CC=arm-linux-gnueabi-gcc
EOF
# Create the source.
cat << _EOF_ > hello.go
package main
func main() {
println("hello")
}
_EOF_
# Create go.mod.
go mod init hello && go mod tidy
# Build a docker image.
docker build --tag hello .
--------
Now, this is what I see when building normally:
$ docker run -it --rm -v .:/hello hello
root@42d4fe21de73:/go# cd /hello
root@42d4fe21de73:/hello# go build .
root@42d4fe21de73:/hello# echo $?
0
root@42d4fe21de73:/hello# ls -l hello
-rwxr-xr-x. 1 root root 1218776 Apr 1 20:25 hello
Now let's add -buildmode=pie:
root@42d4fe21de73:/hello# rm hello
root@42d4fe21de73:/hello# go build -buildmode=pie .
# hello
loadinternal: cannot find runtime/cgo
root@42d4fe21de73:/hello# echo $?
0
root@42d4fe21de73:/hello# ls -l hello
-rwxr-xr-x. 1 root root 1121328 Apr 1 20:26 hello
Now, let's enable CGO (since it's disabled by default when cross-compiling):
root@42d4fe21de73:/hello# CGO_ENABLED=1 go build -buildmode=pie .
root@42d4fe21de73:/hello# ls -l hello
-rwxr-xr-x. 1 root root 1143380 Apr 1 20:27 hello
System info:
root@42d4fe21de73:/hello# env
HOSTNAME=42d4fe21de73
PWD=/hello
GOARCH=arm
container=podman
GOARM=6
HOME=/root
GOLANG_VERSION=1.18
TERM=xterm
HOST=arm-linux-gnueabi
SHLVL=1
PATH=/go/bin:/usr/local/go/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
CC=arm-linux-gnueabi-gcc
OLDPWD=/go
GOPATH=/go
_=/usr/bin/env
root@42d4fe21de73:/hello# go env
GO111MODULE=""
GOARCH="arm"
GOBIN=""
GOCACHE="/root/.cache/go-build"
GOENV="/root/.config/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct";
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="go1.18"
GCCGO="gccgo"
GOARM="6"
AR="ar"
CC="arm-linux-gnueabi-gcc"
CXX="g++"
CGO_ENABLED="0"
GOMOD="/hello/go.mod"
GOWORK=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -marm -fmessage-length=0
-fdebug-prefix-map=/tmp/go-build3607723978=/tmp/go-build
-gno-record-gcc-switches"
root@42d4fe21de73:/hello# $CC --version
arm-linux-gnueabi-gcc (Debian 10.2.1-6) 10.2.1 20210110
Copyright (C) 2020 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
root@42d4fe21de73:/hello# go version
go version go1.18 linux/amd64
root@42d4fe21de73:/hello#
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