What should I do if I want to add a new independent binary target.

[Squirre17]

this is my dir tree

$ tree      
.
├── build
│   └── linux
│       └── x86_64
│           └── debug
├── inc
│   ├── debug.h
│   ├── elfinfo.h
│   └── types.h
├── README.md
├── shellcode
│   ├── prelude.S
│   └── shellcode.S
├── src
│   ├── elfinfo.c
│   ├── main.c
│   └── prelude_inc.S
└── xmake.lua

I want shellcode/prelude.S will be compiled into prelode.bin independently. and then use objcopy to get a raw binary.
But I found it will only add a .o file if I add a target entry.

add_rules("mode.debug", "mode.release")

-- Add prelude target
target("prelude.bin")
    set_kind("binary")
    add_files("shellcode/prelude.S")

    -- Add custom command to generate prelude.bin
    after_build(function (target) 
        os.exec("objcopy -O binary --only-section=.text %s %s", target:objectfile() ,target:targetfile()) 
    end)

-- -- Add shellcode target
-- target("shellcode")
--     set_kind("binary")
--     add_files("shellcode/shellcode.S")

--     -- Add custom command to generate shellcode.bin
--     add_custom_command("shellcode.bin", function (target)
--             os.runv("gcc", {"-nostdlib", "-o", "shellcode.o", "shellcode.S"})
--             os.runv("objcopy", {"-O", "binary", "--only-section=.text", "shellcode.o", "shellcode.bin"})
--         end,
--         {dependfile = "shellcode.S"})


target("ElfInject")
    add_includedirs("inc")
    set_kind("binary")
    
    if is_mode("debug") then 
        add_cxflags("-g") 
        add_cxflags("-O0") 
    end
    
    add_files("src/*.S")
    add_files("src/*.c")

[waruqi]

target:objectfiles()[1]