[RFC PATCH v3 01/22] kernel: configs: add qemu-busybox-min.config

[Ariel Miculas <amiculas@cisco.com>]

This is a minimal configuration for running a busybox initramfs image
with networking support. Added for convenience.

Signed-off-by: Ariel Miculas <amiculas@cisco.com>
---
 arch/x86/configs/qemu-busybox-min.config | 11 +++++
 kernel/configs/qemu-busybox-min.config   | 56 ++++++++++++++++++++++++
 2 files changed, 67 insertions(+)
 create mode 100644 arch/x86/configs/qemu-busybox-min.config
 create mode 100644 kernel/configs/qemu-busybox-min.config

diff --git a/arch/x86/configs/qemu-busybox-min.config b/arch/x86/configs/qemu-busybox-min.config
new file mode 100644
index 000000000000..9a2bf2549053
--- /dev/null
+++ b/arch/x86/configs/qemu-busybox-min.config
@@ -0,0 +1,11 @@
+CONFIG_64BIT=y
+CONFIG_ACPI=y
+
+CONFIG_SERIAL_8250=y
+CONFIG_SERIAL_8250_CONSOLE=y
+
+CONFIG_HYPERVISOR_GUEST=y
+CONFIG_PVH=y
+
+CONFIG_CMDLINE_BOOL=y
+CONFIG_CMDLINE="console=ttyS0 nokaslr rdinit=/sbin/init"
diff --git a/kernel/configs/qemu-busybox-min.config b/kernel/configs/qemu-busybox-min.config
new file mode 100644
index 000000000000..51435e178199
--- /dev/null
+++ b/kernel/configs/qemu-busybox-min.config
@@ -0,0 +1,56 @@
+# This is a minimal configuration for running a busybox initramfs image with
+# networking support.
+#
+# The following command can be used create the configuration for a minimal
+# kernel image:
+#
+# make allnoconfig qemu-busybox-min.config
+#
+# The following command can be used to build the configuration for a default
+# kernel image:
+#
+# make defconfig qemu-busybox-min.config
+#
+# On x86, the following command can be used to run qemu:
+#
+# qemu-system-x86_64 -nographic -kernel vmlinux -initrd initrd.img -nic user,model=rtl8139,hostfwd=tcp::5555-:23
+#
+# On arm64, the following command can be used to run qemu:
+#
+# qemu-system-aarch64 -M virt -cpu cortex-a72 -nographic -kernel arch/arm64/boot/Image -initrd initrd.img -nic user,model=rtl8139,hostfwd=tcp::5555-:23
+
+CONFIG_SMP=y
+CONFIG_PRINTK=y
+CONFIG_PRINTK_TIME=y
+
+CONFIG_PCI=y
+
+# We use an initramfs for busybox with elf binaries in it.
+CONFIG_BLK_DEV_INITRD=y
+CONFIG_RD_GZIP=y
+CONFIG_BINFMT_ELF=y
+CONFIG_BINFMT_SCRIPT=y
+
+# This is for /dev file system.
+CONFIG_DEVTMPFS=y
+
+# Core networking (packet is for dhcp).
+CONFIG_NET=y
+CONFIG_PACKET=y
+CONFIG_INET=y
+
+# RTL8139 NIC support.
+CONFIG_NETDEVICES=y
+CONFIG_ETHERNET=y
+CONFIG_NET_VENDOR_REALTEK=y
+CONFIG_8139CP=y
+
+# To get GDB symbols and script.
+CONFIG_DEBUG_KERNEL=y
+CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT=y
+CONFIG_GDB_SCRIPTS=y
+
+# For the power-down button (triggered by qemu's `system_powerdown` command).
+CONFIG_INPUT=y
+CONFIG_INPUT_EVDEV=y
+CONFIG_INPUT_KEYBOARD=y
-- 
2.34.1