DEV Community: Wataru Ashihara

Chrome attach debug with WebStorm

Wataru Ashihara — Mon, 04 Nov 2019 09:07:12 +0000

1) Launch chrome with a command described in vscode-chrome-debug - Attach. Here we use port 9929 for the Chrome Debugging protocol (--remote-debugging-port=9229). Confirm that chrome properly listens the port:

$ netstat -an | grep 9229
tcp        0      0 127.0.0.1:9229          0.0.0.0:*               LISTEN

$ lsof -i :9229
COMMAND   PID USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
chrome  18347  wsh  132u  IPv4 729759      0t0  TCP localhost:9229 (LISTEN)

2) On WebStorm, create a Configuration of "Attach to Node.js/Chrome":

3) Start debug with the created configuration. A dialog appears with the list of the opened tabs, then choose the one you want to debug (Here I choose Friendly Chat from Firebase tutorial).

Way to go!

How to create and debug Ruby gem with C (native) extension

Wataru Ashihara — Sat, 16 Feb 2019 15:10:17 +0000

Moved to https://blog.wataash.com/ruby-c-extension/

Create compilation database (compile_commands.json) for NetBSD-kernel source

Wataru Ashihara — Sun, 23 Dec 2018 09:29:18 +0000

にほんご

Source code structure of NetBSD kernel (netbsd-src/sys/) is so complicated that it is almost impossible for a static-source-analysis tool to provide an accurate location of a symbol. For an example, cscope can't understand where <machine/endian.h> is:

sys/arch/hpc/stand/include/machine/endian.h?
or sys/arch/hpcmips/stand/include/machine/endian.h?

Actually it's ${OBJDIR}/sys/arch/amd64/compile/GENERIC/machine/endian.h! cscope doesn't know that the compilation is done in ${OBJDIR}/sys/arch/amd64/compile/GENERIC with the -I. flag.

To realize an accurate code analysis, compiling information is needed -- so-called compilation database or compile_commands.json.

Here's how to create compile_commands.json for NetBSD kernel on Linux (Ubuntu 18.04):
(I'll write additional information when it's done on NetBSD and macOS soon... NetBSD may be faceed with an issue in bear. And it's may be avoided by using scan-build)



# https://github.com/rizsotto/Bear/
sudo apt install bear

cd netbsd-src/

# First, create ${OBJDIR}/sys/arch/amd64/compile/GENERIC/Makefile
# and confirm that the kernel can be built
./build.sh kernel=GENERIC

cd ${OBJDIR}/sys/arch/amd64/compile/GENERIC/
${TOOLDIR}/bin/nbmake-amd64 clean
bear ${TOOLDIR}/bin/nbmake-amd64             # creates compile_commands.json
mv compile_commands.json ${NETBSD-SRC}/sys/  # optional

Then open the kernel sources with your preferred editor that supports compilation database, such like vim with YouCompleteMe or CLion (used in this article). You may get errors from cc:



Compiler exited with error code 1: /usr/bin/cc -xc -c -mcmodel=kernel (snip) -v -dD -E
    Using built-in specs.
    (snip)
    End of search list.
    cc1: error: code model kernel does not support PIC mode

The editor executes /usr/bin/cc for the code analysis, whereas it's should be ${TOOLDIR}/bin/x86_64--netbsd-gcc[--<target>] This problem can be resolved by simply replacing the path to the compiler:



cp compile_commands.json compile_commands.json.bak
sed -i s!'"cc",'!'"/home/wsh/src/netbsd/tools/bin/x86_64--netbsd-gcc",'!g compile_commands.json

Enjoy code jumping!

For maintainers of official documentations

I'd be glad to migrate all or part of this and other articles to official documentations. Please make a comment here or contact me to do so.

QEMU options for debugging kernel

Wataru Ashihara — Thu, 22 Nov 2018 15:50:31 +0000

Sec.: sections in qemu-doc(1)

Sec.	Option	Details
2.3.1	`-smp 4`	Simulate an SMP system with 4 CPUs
2.3.1	`-m 256`	Memory 256MiB
2.3.2	`-hda netbsd.qcow2`	Use `netbsd.qcow2` as hard disk 0
2.3.3	`-cdrom netbsd.iso`	Use `netbsd.iso` as CD-ROM image
2.3.4	`-display curses`	Use curses display instead of VGA output; Connect QEMU monitor and `q` to quit
2.3.4	`-display none`	Don't show VGA display
2.3.4	`-nographic`	`-display none` + `-parallel null`(if `-parallel` not specified) + `-serial mon:stdio`(if `-serial` and `-monitor` not specified); undocumented, investigated by debugging QEMU
2.3.6	`-netdev user,id=n1,hostfwd=tcp::10022-:22 -device e1000,netdev=n1`	User mode network stack (NAT Network in VirtualBox); forwarding localhost:10022 to guest's port 22
2.3.6	`-nic user,hostfwd=tcp::10022-:22`	Shorthand for above; requires QEMU (>= 2.12)
2.3.11	`-serial telnet::5555,server,nowait`	`telnet localhost 5555` to get serial I/O
2.3.11	`-monitor telnet::5556,server,nowait`	`telnet localhost 5556` to connect QEMU monitor
2.3.11	`-serial mon:telnet::5555,server,nowait`	Serves both serial and monitor via `telnet localhost 5555`; Ctrl-a h to see help
2.3.11	`-serial mon:stdio`	Serves both serial and monitor on the terminal; Ctrl-a h to see help
2.3.11	`-S`	Stop running machine until gdbserver accepts a connection
2.3.11	`-gdb tcp::1234`	Listen gdb connection on port 1234
2.3.11	`-s`	Shorthand for `-gdb tcp::1234`
2.3.11	`-enable-kvm`	(Linux only) Enable KVM support
2.3.11	`-no-reboot`	`reboot` コマンドで再起動せずにQEMUを終了する
2.3.11	`-daemonize`	Daemonize QEMU; Useful when QEMU runs long time since QEMU won't killed (SIGHUP'ed) on the terminal closed
2.3.11	`-rtc base=utc`	To correct timezone

I'll add Linux-specific options (such as -kernel)