how to explain this line ?

[horseriver]

hi:)

  I am newbie. can you help me with these lines ?
  
  ***
  quiet_cmd_syscall = SYSCALL $@
      cmd_syscall = $(CC) --disable-linker-build-id -nostdlib 
$(SYSCFLAGS_$(@F)) \
                            -Wl,$(filter-out FORCE,$^) -o $@

  $(obj)/vsyscall-int80.so $(obj)/vsyscall-sysenter.so: \
  $(obj)/vsyscall-%.so: $(src)/vsyscall.lds $(obj)/vsyscall-%.o FORCE
                       $(call if_changed,syscall)
  ***
 

  $(filter-out FORCE,$^) represent what?

  

thanks!