Please answer these questions before submitting your issue. Thanks!

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

go version go1.10rc1 freebsd/amd64

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

go env
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/sternix/.cache/go-build"
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="freebsd"
GOOS="freebsd"
GOPATH="/home/sternix/go"
GORACE=""
GOROOT="/opt/go/1_10rc1/go"
GOTMPDIR=""
GOTOOLDIR="/opt/go/1_10rc1/go/pkg/tool/freebsd_amd64"
GCCGO="gccgo"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build393653327=/tmp/go-build -gno-record-gcc-switches"

What did you do?

package main

import (
        "fmt"
        "log"
        "net/http"
)

func index(w http.ResponseWriter, r *http.Request) {
        fmt.Fprintf(w,"Hello World")
}

func main() {
        http.HandleFunc("/",index)

        if err := http.ListenAndServe(":8080",nil); err != nil {
                log.Fatal(err)
        }
}

What did you expect to see?

compiled with go 1.9.2
% netstat -Lan
Current listen queue sizes (qlen/incqlen/maxqlen)
Proto Listen Local Address
tcp46 0/0/65535 *.8080

compiled with go 1.10rc1
% netstat -Lan
Current listen queue sizes (qlen/incqlen/maxqlen)
Proto Listen Local Address
tcp46 0/0/128 *.8080

i want to see
tcp46 0/0/65535 *.8080

i suspect the
e76ae8a#diff-871343a875351732bbc01da3b532b485
the pr cause this

because FreeBSD has " kern.ipc.soacceptqueue "," kern.ipc.somaxconn " sysctl's but no
" kern.ipc.acceptqueue "

% sysctl kern.ipc.soacceptqueue
kern.ipc.soacceptqueue: 65536

% sysctl kern.ipc.somaxconn
kern.ipc.somaxconn: 65536

% sysctl kern.ipc.acceptqueue
sysctl: unknown oid 'kern.ipc.acceptqueue'

package main

import (
        "syscall"
        "fmt"
)

func maxListenerBacklog() int {
        n, err := syscall.SysctlUint32("kern.ipc.acceptqueue")
        if n == 0 || err != nil {
                fmt.Printf("Error: %s\n",err)
                return syscall.SOMAXCONN

                // https://github.com/golang/go/blob/master/src/syscall/zerrors_freebsd_amd64.go#L1288
                // SOMAXCONN = 0x80
                // defaults to 128
        }

        // FreeBSD stores the backlog in a uint16, as does Linux.
        // Assume the other BSDs do too. Truncate number to avoid wrapping.
        // See issue 5030.
        if n > 1<<16-1 {
                n = 1<<16 - 1
        }
        return int(n)
}

func maxListenerBacklogCorrect() int {
        n, err := syscall.SysctlUint32("kern.ipc.soacceptqueue")
        if n == 0 || err != nil {
                return syscall.SOMAXCONN
        }
        // FreeBSD stores the backlog in a uint16, as does Linux.
        // Assume the other BSDs do too. Truncate number to avoid wrapping.
        // See issue 5030.
        if n > 1<<16-1 {
                n = 1<<16 - 1
        }
        return int(n)
}

func main() {
        bl := maxListenerBacklog()
        fmt.Printf("Wrong Backlog: %d\n",bl)

        bl = maxListenerBacklogCorrect()
        fmt.Printf("Correct Backlog: %d\n",bl)
}

after all, i think the line in
https://github.com/golang/go/blob/master/src/net/sock_bsd.go#L23
might be
n, err = syscall.SysctlUint32("kern.ipc.soacceptqueue")

Can you help.