The bug report is asking for at least the following system calls to be added to the FreeBSD target:

SYS_SEMOP
SYS_SEMGET
SYS_SEMCTL
SYS_MSGSND
SYS_MSGRCV
SYS_MSGGET
SYS_MSGCTL
SYS_SHMAT
SYS_SHMDT
SYS_SHMGET

These values should not be added to the syscall package, which is frozen, but they should be added to the golang.org/x/sys/unix package.

Actually, all system calls that are defined in the FreeBSD kernel should be defined in go, including module-dependent ones.

@yurivict I agree. Not sure what you mean by writing "actually."

Some of the system calls are labeled as optional. All of them, including the optional ones, should be available in go.

Just poking around to see why this is, and it looks like there are a lot of un-implemented system calls. See syscall_freebsd.go

The mksysnum_freebsd.pl regex filters syscalls of type NOSTD which accounts for missing ones.

mksysnum_freebsd.pl shouldn't filter out NOSTD calls.
They are regular calls defined in kernel modules that might be missing on some systems, but are usually present.

Change https://golang.org/cl/129855 mentions this issue: unix: add NOSTD syscall numbers on FreeBSD