configs/qemu_riscv32_virt: new defconfig

Add RISC-V 32-bit defconfig for QEMU virt machine.

Tested with QEMU 2.12.1

Signed-off-by: Mark Corbin <mark.corbin@embecosm.com>
Reviewed-by: Matt Weber <matthew.weber@rockwellcollins.com>
[Thomas: regenerate .gitlab-ci.yml, update DEVELOPERS file]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

.gitlab-ci.yml

@@ -230,6 +230,7 @@ qemu_ppc64le_pseries_defconfig: *defconfig
 qemu_ppc_g3beige_defconfig: *defconfig
 qemu_ppc_mpc8544ds_defconfig: *defconfig
 qemu_ppc_virtex_ml507_defconfig: *defconfig
+qemu_riscv32_virt_defconfig: *defconfig
 qemu_riscv64_virt_defconfig: *defconfig
 qemu_sh4_r2d_defconfig: *defconfig
 qemu_sh4eb_r2d_defconfig: *defconfig

DEVELOPERS

@@ -1351,8 +1351,10 @@ F:	package/ratpoison/
 N:	Mark Corbin <mark.corbin@embecosm.com>
 F:	arch/arch.mk.riscv
 F:	arch/Config.in.riscv
+F:	board/qemu/riscv32-virt/
 F:	board/qemu/riscv64-virt/
 F:	boot/riscv-pk/
+F:	configs/qemu_riscv32_virt_defconfig
 F:	configs/qemu_riscv64_virt_defconfig
 
 N:	Markos Chandras <markos.chandras@imgtec.com>

board/qemu/riscv32-virt/linux.config

@@ -0,0 +1,23 @@
+CONFIG_ARCH_RV32I=y
+CONFIG_SMP=y
+CONFIG_NR_CPUS=8
+CONFIG_PCI=y
+CONFIG_SYSVIPC=y
+CONFIG_NET=y
+CONFIG_PACKET=y
+CONFIG_UNIX=y
+CONFIG_INET=y
+# CONFIG_WIRELESS is not set
+CONFIG_VIRTIO_BLK=y
+CONFIG_NETDEVICES=y
+CONFIG_VIRTIO_NET=y
+# CONFIG_ETHERNET is not set
+# CONFIG_WLAN is not set
+CONFIG_SERIAL_8250=y
+CONFIG_SERIAL_8250_CONSOLE=y
+CONFIG_SERIAL_OF_PLATFORM=y
+CONFIG_VIRT_DRIVERS=y
+CONFIG_VIRTIO_MMIO=y
+CONFIG_EXT2_FS=y
+CONFIG_EXT4_FS=y
+CONFIG_TMPFS=y

board/qemu/riscv32-virt/readme.txt

@@ -0,0 +1,7 @@
+Run the emulation with:
+
+  qemu-system-riscv32 -M virt -kernel output/images/bbl -append "root=/dev/vda ro console=ttyS0" -drive file=output/images/rootfs.ext2,format=raw,id=hd0 -device virtio-blk-device,drive=hd0 -netdev user,id=net0 -device virtio-net-device,netdev=net0 -nographic
+
+The login prompt will appear in the terminal that started Qemu.
+
+Tested with QEMU 2.12.1

configs/qemu_riscv32_virt_defconfig

@@ -0,0 +1,25 @@
+# Architecture
+BR2_riscv=y
+BR2_RISCV_32=y
+
+# System
+BR2_SYSTEM_DHCP="eth0"
+BR2_TARGET_GENERIC_GETTY=y
+BR2_TARGET_GENERIC_GETTY_PORT="ttyS0"
+
+# Filesystem
+BR2_TARGET_ROOTFS_EXT2=y
+
+# Linux headers same as kernel, a 4.15 series
+BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_4_15=y
+
+# Kernel
+BR2_LINUX_KERNEL=y
+BR2_LINUX_KERNEL_CUSTOM_GIT=y
+BR2_LINUX_KERNEL_CUSTOM_REPO_URL="https://github.com/riscv/riscv-linux.git"
+BR2_LINUX_KERNEL_CUSTOM_REPO_VERSION="fe92d7905c6ea0ebeabeb725b8040754ede7c220"
+BR2_LINUX_KERNEL_USE_CUSTOM_CONFIG=y
+BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE="board/qemu/riscv32-virt/linux.config"
+
+# Bootloader
+BR2_TARGET_RISCV_PK=y