This page explains how to build up environment to develop QEMU SH4 System Emulation. These works are done 2008 March, on Ubuntu Edgy.

QEMU

Get qemu-0.9.1, and build it.

    % wget http://fabrice.bellard.free.fr/qemu/qemu-0.9.1.tar.gz
    % tar zxvf ./qemu-0.9.1.tar.gz
    % cd ./qemu-0.9.1
    % ./configure --target-list=sh4-softmmu,sh4-linux-user
    % make

I recommend to specify --target-list option to reduce build time.

Linux Kernel and Userland

Build Linux Kernel for SH according to LinuxSH Wiki. First of all, obtain the toolchain fro SH4.

    % mkdir /opt/gnush4
    % cd /opt/gnush4
    % wget http://userweb.kernel.org/~lethal/toolchains/gnush4_linux_v0702_rc-1-1.i386.tar.gz
    % tar zxvf gnush4_linux_v0702_rc-1-1.i386.tar.gz

Then obtain kernel source. I followed git-howto. Git-clone takes a long time.

    % git-clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git linux-2.6
    % cd linux-2.6
    % git pull git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git

Configure kernel. I chose R2D+ for the target hardware emulated by QEMU.

    % cp ./arch/sh/configs/rts7751r2dplus_defconfig .config
    % make ARCH=sh CROSS_COMPILE=/opt/gnush4/usr/share/gnush4_linux_v0702_rc-1/bin/sh4-linux- menuconfig

Some R2D+ hardware options cause kernel boot failure because QEMU cannot emulate them yet. So you need disable them with menu.

Bus options --> PCI support
Network --> Networking support
Device Drivers --> Serial ATA (prod) and Parallel ATA (experimental) drivers --> Serial ATA (prod) and Parallel ATA (experimental) drivers
Device Drivers --> SPI support --> SuperH SCI SPI controller (CONFIGSPISH_SCI)
Device Drivers --> USB support

I chose Eerly User Space (INITRAMFS) for the userland. Minimum set of userland is original 'init' and /dev/console. For 'init' write a hello.c which prints the 'Hello Wolrd' message. Then, these operations give us a tiny userland.

     % mkdir (somewhere)/rootfs
     % cd (somewhere)/rootfs
     % /opt/gnush4/usr/share/gnush4_linux_v0702_rc-1/bin/sh4-linux-gcc (somewhere)/hello.c -static -o init
     % mkdir dev
     % cd dev
     % sudo mknod console c 5 1

Invoke kernel menuconfig again, and enable INITRAMFS.

General Setup --> Initial RAM filesystem and RAM disk (initramfs/initrd) support

And set Initramfs source file, (somewhere)/rootfs.

At last, build kernel.

    % make ARCH=sh CROSS_COMPILE=/opt/gnush4/usr/share/gnush4_linux_v0702_rc-1/bin/sh4-linux- zImage

How to invoke QEMU

The command I use is like this.

     % ./qemu/sh4-softmmu/qemu-sh4 -m r2d -serial vc -serial stdio -d in_asm -kernel ./linux-2.6/arch/sh/boot/zImage

The vc serial console shows QEMU monitor, which is easy to quit QEMU cleanly with 'q' command. The '-d in_asm' options logs compiled SH assembler code into /tmp/qemu.log, which tells us how QEMU operations proceed.