You did nothing wrong, in 1.11 we started compressing the debug information
to reduce binary size, and gdb on the Mac does not understand compressed
DWARF.
We had hoped that the several speedbumps involved in running gdb on modern
OSX would have caused most users to move to Delve, which handles compressed
DWARF, but obviously this was overoptimistic.
The workaround is to also specify "-ldflags=-compressdwarf=false" which
does exactly what it claims.
If you wanted to do this generally (so you did not need to remember),
export GOFLAGS="-ldflags=-compressdwarf=false"
You might try not specifying "-N -l" and see whether optimized binaries
have adequate debugging information; it's not perfect, but we are hoping to
get it good enough that core dumps and probes from/on running applications
will yield useful information.
Sorry for the inconvenience.
On Thursday, September 27, 2018 at 9:38:23 AM UTC-4, changkun wrote:
>
> Debugging with GDB works fine on Linux, it is able to show everything
> with the breakpoint. However, nothing appears on macOS.
>
> A simple Go program, say `main.go`:
>
> package main
>
> func main() {
> println("hello, world!")
> }
>
>
> Then build with
>
> go build -gcflags "-N -l" -o main main.go
>
>
> Using GDB:
>
> $ gdb main
> GNU gdb (GDB) 8.2
> (...)
> Reading symbols from main...(no debugging symbols found)...done.
> Loading Go Runtime support.
> (gdb) source /usr/local/Cellar/go/1.11/libexec/src/runtime/runtime-gdb
> .py
> Loading Go Runtime support.
> (gdb) info files
> Symbols from "/Users/changkun/Desktop/demo/main".
> Local exec file:
> `/Users/changkun/Desktop/demo/main', file type mach-o-x86-64.
> Entry point: 0x1049e20
> 0x0000000001001000 - 0x000000000104dfcf is .text
> 0x000000000104dfe0 - 0x0000000001077344 is __TEXT.__rodata
> (...)
> (gdb) b *0x1049e20
> Breakpoint 1 at 0x1049e20
> (gdb)
>
>
> There is no `at` in the GDB outputs, the version of Go is `go version
> go1.11 darwin/amd64` and:
>
> $ ls -al /usr/local/bin | grep go
> lrwxr-xr-x 1 changkun admin 24 Aug 25 16:37 go -> ../Cellar
> /go/1.11/bin/go
>
>
>
> ======
>
> Same process in linux environment:
>
> docker run -it --rm --name golang golang:1.11 bash
>
> then entering container install `gdb`
>
> root@1326d3f1a957:/# gdb main
> GNU gdb (Debian 7.12-6) 7.12.0.20161007-git
> (...)
> (gdb) info files
> Symbols from "/main".
> Local exec file:
> `/main', file type elf64-x86-64.
> Entry point: 0x44a2e0
> 0x0000000000401000 - 0x000000000044ea8f is .text
> (...)
> (gdb) b *0x44a2e0
> Breakpoint 1 at 0x44a2e0: file
> /usr/local/go/src/runtime/rt0_linux_amd64.s, line 8.
> (gdb)
>
>
> Linux is able to show with a breakpoint, `(gdb) b *0x44a2e0
> Breakpoint 1 at 0x44a2e0: file
> /usr/local/go/src/runtime/rt0_linux_amd64.s, line 8.`
>
> What did I do wrong on macOS? How can I perform low-level debugging for Go
> programs on macOS with GDB?
>
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