Ubuntu 16.04: Run Fuchsia on QEMU

Table of Contents

1 Run Fuchsia

Run Fuchsia with magenta/docs/getting_started.md.

1.1 Download

Download Fuchsia from repository.

$ git clone

1.2 Install packages

Install packages for building Fuchsia.

$ sudo apt install -y texinfo libglib2.0-dev autoconf libtool libsdl-dev build-essential

1.3 toolchain

Download toolchain.

$ ./scripts/download-toolchain

This will be stored at prebuilt/downloads.

$ ls prebuilt/downloads/aarch64-elf-5.3.0-Linux-x86_64 arm-eabi-Linux-x86_64.tar.bz2aarch64-elf-Linux-x86_64.stamp x86_64-elf-5.3.0-Linux-x86_64aarch64-elf-Linux-x86_64.tar.bz2 x86_64-elf-Linux-x86_64.stamparm-eabi-5.3.0-Linux-x86_64 x86_64-elf-Linux-x86_64.tar.bz2

The GDB in prebuilt/downloads does not have layout command. This article will use layout command and build toolchain. Building toolchain will take about 2 hours.

$ sudo apt build-dep -y gcc gdb$ git clone cd gcc_none_toolchains$ ./doit -a ‘arm aarch64 x86_64’ -f$ cd ..

1.4 Build

Build binary of target board with make.

$ make <target>

The binary will be stored at build-<target>.


This article will use magenta-pc-x86-64

$ make magenta-pc-x86-64

The list of <target> is as below. Running make without target will use magenta-pc-x86-64.

$ make listList of all buildable projects: (look in project/ directory)qemu-virt-a53-testrpi3-testmagenta-pc-x86-64pc-x86-64-testmagenta-qemu-arm32pc-x86-testqemu-virt-a15-testmagenta-qemu-arm64

1.5 QEMU

The QEMU in Fuchsia’s repository has few patches. Build QEMU in Fuchsia’s repository and install it.

$ sudo apt build-dep -y qemu$ git clone mkdir qemu.build$ cd qemu.build$ ../qemu/configure –target-list=arm-softmmu,aarch64-softmmu,x86_64-softmmu$ make && sudo make install

Run QEMU with script.

$ ./scripts/run-magenta-x86-64

The arguments of script are as below.

$ ./scripts/run-magenta-x86-64 -hhelp:-a <arch> : arm32, arm64, or x86-64-b : build first-c : add item to kernel commandline-d : run with emulated disk-g : use graphical console-k : use KVM-m <memory in MB> : default 512MB-n : run with emulated nic-N : run with emulated nic via tun/tap-o <dir> : build directory-r : run release build-u : use uniprocessor-v : use vnc based display-x <bootfs> : add eXtra bootfs-h for helpall arguments after — are passed to qemu directly

2 Debug with GDB-stub.

This article will debug kernel and uapp with GDB-stub.

2.1 QEMU

Change QEMU script as below.

diff –git a/scripts/run-magenta b/scripts/run-magentaindex 555c64d..e1102ae 100755— a/scripts/run-magenta+++ b/scripts/run-magenta@@ -22,6 +22,7 @@ function HELP { echo “-u : use uniprocessor” echo “-v : use vnc based display” echo “-x <bootfs> : add eXtra bootfs”+ echo “-G <port> : gdb port” echo “-h for help” echo “all arguments after — are passed to qemu directly” exit 1@@ -43,8 +44,9 @@ RELEASE=0 VNC=0 INITRD= CMDLINE=””+GDBPORT=””-while getopts a:Abc:dgkm:nNo:ruvx:h FLAG; do+while getopts a:Abc:dgkm:nNo:ruvx:G:h FLAG; do case $FLAG in a) ARCH=$OPTARG;; A) AUDIO=1;;@@ -61,6 +63,7 @@ while getopts a:Abc:dgkm:nNo:ruvx:h FLAG; do u) UP=1;; v) VNC=1;; x) INITRD=$OPTARG;;+ G) GDBPORT=$OPTARG;; h) HELP;; ?) echo unrecognized option@@ -189,6 +192,11 @@ if [ “$INITRD” != “” ]; then ARGS+=” -initrd $INITRD” fi+# gdb port+if [ “$GDBPORT” != “” ]; then+ ARGS+=” -gdb $GDBPORT -S”+fi+ # run qemu echo $QEMU $ARGS -append “$CMDLINE” $@ $QEMU $ARGS -append “$CMDLINE” $@

Run QEMU with -G option.

$ ./scripts/run-magenta-x86-64 -G tcp::10000

2.2 GDB

x86_64-elf-5.3.0-Linux-x86_64/bin/x86_64-elf-gdb will cause below error.

Remote ‘g’ packet reply is too long: 000000000…

This article will use gdb64 in Ubuntu 16.04 because it will not cause error.

$ sudo apt install -y gdb64

Use the following GDB script.

$ cat gdb.xsymbol-file build-magenta-pc-x86-64/magenta.elfset architecture i386:x86-64target remote localhost:10000b lk_mainla srcc

Run GDB with script.

$ gdb64 -x gdb.x

In case of scripts/run-magenta-arm64, please use gcc_none_toolchains/aarch64-elf-5.3.0-Linux-x86_64/bin/aarch64-elf-gdb.

2.3 Execution result

After running arch-depend assembler, lk_main function will be called.

kernel/arch/xxx/xxx/start.S -> lk_main at kernel/top/main.c

GDB break at lk_main as below.


2.4 Debug userboot with GDB-stub

The userboot is a program running from kernel to userspace. This looks like init programe in Linux.

bootstrap2 (kernel) -> userboot_init (kernel) -> userboot (uapp) -> … -> bin/mxsh (uapp)

The load address of userboot (uapp) will be output.

[00001.069] K userboot: userboot-code 0x2000 @ [0x1002000,0x1004000)

Add userboot (uapp) symbol with add-symbol-file in GDB script.

$ cat gdb.xsymbol-file build-magenta-pc-x86-64/magenta.elfset architecture i386:x86-64target remote localhost:10000add-symbol-file build-magenta-pc-x86-64/uapp/userboot/libuserboot.so 0x1002000b _startla srcc

When running QEMU and GDB, GDB break at _start function in userboot (uapp) as below.


It might be enable to debug bin/devmgr if knowing load address (This article cannot get load address).

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