What version of Go are you using (go version)?

$ go version
go version go1.14.7 aix/ppc64

Does this issue reproduce with the latest release?

This is the latest release available from IBM

What operating system and processor architecture are you using (go env)?

$ go env
GO111MODULE=""
GOARCH="ppc64"
GOBIN=""
GOCACHE="/root/.cache/go-build"
GOENV="/root/.config/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="ppc64"
GOHOSTOS="aix"
GOINSECURE=""
GONOPROXY=""
GONOSUMDB=""
GOOS="aix"
GOPATH="/root/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/opt/freeware/lib/golang"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/opt/freeware/lib/golang/pkg/tool/aix_ppc64"
GCCGO="gccgo"
GOPPC64="power8"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -maix64 -pthread -mcmodel=large -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build467576586=/tmp/go-build -gno-record-gcc-switches"

What did you do?

compiling a package:
./segment-readonly.go:12:5: undefined: unix.Access

What did you expect to see?

the package is compiled.

What did you see instead?

./segment-readonly.go:12:5: undefined: unix.Access

The problem is missing Access() in golang.org/x/sys/unix on AIX platform. AIX has access() syscall and is fully compatible with the Linux counterpart:

Syntax

       #include  
       int access (PathName,Mode)
       char *PathName;
       int Mode;

AFAIU it is just an addition of a line something like:

//sys        Access(path string, mode uint32) (err error)

into syscall_aix.go