在探索pbuilder的用法时，不小心突然在Debian(bulleye)上把riscv qemu安装上了，效果体验还是不错的，故在这里记录一下，以备使用时方便参考。
创建 riscv64 chroot
创建riscv64 的chroot有很多种方式:
debootstrap
sudo apt-get install debootstrap qemu-user-static binfmt-support debian-archive-keyring
sudo debootstrap --arch=riscv64 --keyring /usr/share/keyrings/debian-archive-keyring.gpg --include=debian-archive-keyring unstable /tmp/riscv64-chroot http://deb.debian.org/debian
稍等几分钟，就会创建 /tmp/riscv64-chroot目录，顾名思义，是一个riscv64 的chroot。
debootstrap创建的chroot针对unstable 版本的软件，如果你要使用的软件是来自于unrelease, 则可以参考下面的mmdebstrap.
mmdebstrap
$ sudo apt install mmdebstrap qemu-user-static binfmt-support debian-archive-keyring
$ sudo mmdebstrap --architectures=riscv64 --include="debian-archive-keyring" sid /tmp/riscv64-chroot "deb http://deb.debian.org/debian/ sid main" "deb http://deb.debian.org/debian/ unreleased main"
准备 virtual machine
创建好了 /tmp/riscv64-chroot后，可以开始准备qemu的环境了：
$ sudo chroot /tmp/riscv64-chroot
# Update package information
apt-get update
# Set up basic networking
cat >>/etc/network/interfaces <<EOF
auto lo
iface lo inet loopback
auto eth0
iface eth0 inet dhcp
EOF
# Set root password
# root的登录密码
passwd
# Disable the getty on hvc0 as hvc0 and ttyS0 share the same console device in qemu.
ln -sf /dev/null /etc/systemd/system/[email protected]
# Install kernel and bootloader infrastructure
apt-get install linux-image-riscv64 u-boot-menu
# Install and configure ntp tools
apt-get install openntpd ntpdate
sed -i 's/^DAEMON_OPTS="/DAEMON_OPTS="-s /' /etc/default/openntpd
# Configure syslinux-style boot menu
cat >>/etc/default/u-boot <<EOF
U_BOOT_PARAMETERS="rw noquiet root=/dev/vda1"
U_BOOT_FDT_DIR="noexist"
EOF
u-boot-update
exit
Setting up a riscv64 virtual machine
安装软件
sudo apt install qemu-system-misc opensbi u-boot-qemu
准备chroot
这个chroot就是上文阐述的riscv64 chroot
创建image
sudo apt-get install libguestfs-tools
sudo virt-make-fs --partition=gpt --type=ext4 --size=10G /tmp/riscv64-chroot/ rootfs.img
sudo chown ${USER} rootfs.img
启动 riscv 64 qemu
qemu-system-riscv64 -nographic -machine virt -m 1.9G \
-bios /usr/lib/riscv64-linux-gnu/opensbi/generic/fw_jump.elf \
-kernel /usr/lib/u-boot/qemu-riscv64_smode/uboot.elf \
-object rng-random,filename=/dev/urandom,id=rng0 -device virtio-rng-device,rng=rng0 \
-append "console=ttyS0 rw root=/dev/vda1" \
-device virtio-blk-device,drive=hd0 -drive file=rootfs.img,format=raw,id=hd0 \
-device virtio-net-device,netdev=usernet -netdev user,id=usernet,hostfwd=tcp::22222-:22
默认用户是root， 密码就是上面 passwd命令确认的。
root@debian-local:~# uname -a
Linux debian-local 5.16.0-3-riscv64 #1 SMP Debian 5.16.11-1 (2022-02-25) riscv64 GNU/Linux
退出qemu
qemu: For -nographic just enter:
Ctrl-A X for exit
which means
first press Ctrl + A (A is just key a, not the alt key)->then release the keys->afterwards press(X key)