Is it possible to use Delve to debug the Go runtime function?

[xujintao]

I read the README from https://github.com/go-delve/delve/blob/master/Documentation/faq.md#-using-delve-to-debug-the-go-runtime
I try to step into the build-in print function, but failed.

package main

func main() {
	print(1)
}

Is it possible to use Delve to debug the Go runtime function?

[aarzilli]

Yes

(dlv) b main.main
Breakpoint 1 set at 0x45feca for main.main() ./test.go:3
(dlv) c
> main.main() ./test.go:3 (hits goroutine(1):1 total:1) (PC: 0x45feca)
     1:	package main
     2:	
=>   3:	func main() {
     4:		print(1)
     5:	}
(dlv) disass
TEXT main.main(SB) /home/aa/temp/test.go
	test.go:3	0x45fec0	493b6610	cmp rsp, qword ptr [r14+0x10]
	test.go:3	0x45fec4	7625		jbe 0x45feeb
	test.go:3	0x45fec6	55		push rbp
	test.go:3	0x45fec7	4889e5		mov rbp, rsp
=>	test.go:3	0x45feca*	4883ec08	sub rsp, 0x8
	test.go:4	0x45fece	e8ed49fdff	call $runtime.printlock
	test.go:4	0x45fed3	b801000000	mov eax, 0x1
	test.go:4	0x45fed8	e88350fdff	call $runtime.printint
	test.go:4	0x45fedd	0f1f00		nop dword ptr [rax], eax
	test.go:4	0x45fee0	e83b4afdff	call $runtime.printunlock
	test.go:5	0x45fee5	4883c408	add rsp, 0x8
	test.go:5	0x45fee9	5d		pop rbp
	test.go:5	0x45feea	c3		ret
	test.go:3	0x45feeb	e8f0cdffff	call $runtime.morestack_noctxt
	test.go:3	0x45fef0	ebce		jmp $main.main
(dlv) b runtime.printint
Breakpoint 2 set at 0x434f6a for runtime.printint() /usr/local/go121/src/runtime/print.go:210
(dlv) c
> runtime.printint() /usr/local/go121/src/runtime/print.go:210 (hits goroutine(1):1 total:1) (PC: 0x434f6a)
Warning: debugging optimized function
   205:			v /= 10
   206:		}
   207:		gwrite(buf[i:])
   208:	}
   209:	
=> 210:	func printint(v int64) {
   211:		if v < 0 {
   212:			printstring("-")
   213:			v = -v
   214:		}
   215:		printuint(uint64(v))

[xujintao]

Amazing! Thank you so much.
After i got this, i also found runtime.printint from the disassembly view in vscode, then i added it to the breakpoint list and pressed continue, It works. happy!