add arm64 config

Copy the CONFIG set by virtme into our own config. Use an approach
inspired by merge_config.sh in the kernel source to merge our own
config snippets into alldefconfig.

Reusing merge_config.sh is not an option since the script is overly
simplistic: it doesn't handle trying to set an option which doesn't
exist at all in the kernel and prints an error. This is a problem
for us since we use a single config across many kernel versions.
Some features are only available in new kernels, thus tripping up
merge_config.sh. Instead we use a custom script which has the same
effect but which uses allyesconfig to verify whether a symbol exists.

Signed-off-by: Lorenz Bauer <[email protected]>

Author: lmb

Dockerfile

@@ -9,7 +9,7 @@ RUN --mount=type=cache,target=/tmp/kernel ./download.sh
 
 WORKDIR /usr/src/linux-${KERNEL_VERSION}
 
-COPY configure-vmlinux.sh env.sh config .
+COPY configure-vmlinux.sh env.sh config config-arm64 config-x86_64 .
 
 ARG KBUILD_BUILD_TIMESTAMP="Thu  6 Jul 01:00:00 UTC 2023"
 ARG KBUILD_BUILD_HOST="ci-kernels-builder"

README.md

@@ -11,7 +11,25 @@ You can approximate CI by running `buildx.sh`:
 $ ./buildx.sh 6.1 amd64 vmlinux --tag foo:vmlinux
 ```
 
-# Updating the builder
+## Updating the configuration
+
+The configuration consists of common options in [config](./config) and platform
+specific options in [config-arm64](./config-arm64) and [config-x64_64](./config-x86_64).
+
+To add a new config option:
+
+1. Try adding it to `config` (keep sorted alphabetically)
+2. In a checkout of the Linux source code:
+   ```shell
+   TARGETPLATFORM=linux/arm64 /path/to/configure-vmlinux.sh
+   ```
+3. If any symbols are missing you can now run `make menuconfig` and search for
+   the missing symbols. Figure out which dependencies are missing and add them
+   to the config as well.
+
+Add the config to the arch specific files if it isn't available in general.
+
+## Updating the builder
 
 The builder image is still built manually.
 

config

@@ -1,61 +1,102 @@
 # Kernel config common between arches
 
+# Settings needed to make the vm work.
+CONFIG_9P_FS=y
+CONFIG_BINFMT_SCRIPT=y
+CONFIG_BLK_DEV_INITRD=y
+CONFIG_DEVTMPFS=y
+CONFIG_NET_9P_VIRTIO=y
+CONFIG_NET_9P=y
+CONFIG_NET_CORE=y
+CONFIG_PCI=y
+CONFIG_SYSFS=y
+CONFIG_TMPFS=y
+CONFIG_TTY=y
+CONFIG_UNIX=y
+CONFIG_UNIX98_PTYS=y
+CONFIG_VIRTIO_CONSOLE=y
+CONFIG_VIRTIO_MMIO=y
+CONFIG_VIRTIO_NET=y
+CONFIG_VIRTIO_PCI=y
+CONFIG_VIRTIO=y
+CONFIG_VT=y
+
 # Enable BPF related things
 # Please sort lines by alphabet ascending.
-# CONFIG_UPROBE_EVENT renamed to CONFIG_UPROBE_EVENTS in v4.11
+CONFIG_BPF_JIT_ALWAYS_ON=y
 CONFIG_BPF_JIT=y
 CONFIG_BPF_LIRC_MODE2=y
 CONFIG_BPF_LSM=y
+CONFIG_BPF_PRELOAD=y
 CONFIG_BPF_STREAM_PARSER=y
 CONFIG_BPF_SYSCALL=y
 CONFIG_BPF=y
 CONFIG_BPFILTER=y
 CONFIG_CGROUP_BPF=y
 CONFIG_CGROUP_NET_CLASSID=y
+CONFIG_CGROUPS=y
 CONFIG_DEBUG_INFO_BTF=y
+CONFIG_DEBUG_INFO=y
+CONFIG_DEBUG_KERNEL=y
+CONFIG_DEBUG_INFO_BTF_MODULES=y
 # >= 5.18 has a different toggle for debug info
 CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT=y
-CONFIG_DEBUG_INFO=y
 CONFIG_DYNAMIC_FTRACE=y
 CONFIG_EPOLL=y
 CONFIG_EVENTFD=y
-CONFIG_FPROBE=y
 CONFIG_FTRACE_SYSCALLS=y
+CONFIG_FTRACE=y
 CONFIG_FUNCTION_ERROR_INJECTION=y
+CONFIG_FUNCTION_TRACER=y
+CONFIG_HW_RANDOM=y
 CONFIG_IKCONFIG_PROC=y
 CONFIG_IKCONFIG=y
 CONFIG_INET=y
 CONFIG_IPV6=y
+CONFIG_KPROBES=y
 CONFIG_LIRC=y
+CONFIG_MEDIA_RC_SUPPORT=y
+CONFIG_MEDIA_SUPPORT=y
+CONFIG_MODULES=y
+CONFIG_MULTIUSER=y
 CONFIG_NET=y
 CONFIG_NETFILTER_ADVANCED=y
+CONFIG_NETFILTER=y
+CONFIG_NETWORK_FILESYSTEMS=y
 CONFIG_NF_CONNTRACK_MARK=y
+CONFIG_NF_CONNTRACK=y
+CONFIG_PACKET=y
 CONFIG_PERF_EVENTS=y
+CONFIG_PROC_FS=y
 CONFIG_RC_CORE=y
+CONFIG_RC_DECODERS=y
+CONFIG_SECURITY=y
 CONFIG_SECURITYFS=y
 CONFIG_STACK_TRACER=y
 CONFIG_UPROBE_EVENT=y
 CONFIG_UPROBE_EVENTS=y
 CONFIG_XDP_SOCKETS=y
 
 # VirtIO
-CONFIG_KVM_GUEST=y
 CONFIG_HW_RANDOM_VIRTIO=y
 CONFIG_VIRTIO_BALLOON=y
 
-# Get rid of some drivers
-CONFIG_AGP=n
+# Get rid of some drivers and obsolete features
 CONFIG_ATA=n
 CONFIG_DRM=n
 CONFIG_ETHERNET=n
+CONFIG_EXT3_FS=n
 CONFIG_EXT4_FS=n
 CONFIG_FDDI=n
-CONFIG_HID_GENERIC=n
 CONFIG_HID=n
+CONFIG_INPUT_KEYBOARD=n
+CONFIG_INPUT_MOUSE=n
+CONFIG_INPUT_MOUSEDEV=n
 CONFIG_MD=n
 CONFIG_NFS_FS=n
 CONFIG_PCCARD=n
 CONFIG_SOUND=n
+CONFIG_UEVENT_HELPER=n
 CONFIG_USB_SUPPORT=n
 CONFIG_WIRELESS=n
 CONFIG_WLAN=n

config-arm64

@@ -0,0 +1,6 @@
+# arm64 specific configuration
+
+CONFIG_PCI_HOST_GENERIC=y
+CONFIG_SERIAL_AMBA_PL011_CONSOLE=y
+CONFIG_SERIAL_AMBA_PL011=y
+CONFIG_SERIAL_EARLYCON=y

config-x86_64

@@ -0,0 +1,13 @@
+# amd64 specific configuration
+
+CONFIG_DEBUG_INFO_NONE=n
+CONFIG_DYNAMIC_FTRACE_WITH_REGS=y
+CONFIG_EARLY_PRINTK=y
+CONFIG_FPROBE=y
+CONFIG_HYPERVISOR_GUEST=y
+CONFIG_KVM_GUEST=y
+CONFIG_MAXSMP=y
+CONFIG_PARAVIRT=y
+
+# Get rid of some drivers and obsolete features
+CONFIG_AGP=n

configure-vmlinux.sh

@@ -1,17 +1,104 @@
 #!/bin/bash
-# vmlinux.sh
+# configure-vmlinux.sh
 
 set -eu
 set -o pipefail
 
-source env.sh
+dir="$(dirname "$(realpath "$0")")"
 
-empty_lsmod="$(mktemp)"
-readonly empty_lsmod
+source "$dir/env.sh"
 
-make KCONFIG_CONFIG=custom.config defconfig
-tee -a < "config" custom.config
-make allnoconfig KCONFIG_ALLCONFIG=custom.config
-virtme-configkernel --update
-make localmodconfig LSMOD="${empty_lsmod}"
+# read_config array file
+# read a file in Kconfig format into an associative array.
+#
+# Valid values are "y", "n", "m". Unset options are turned into "n".
+read_config() {
+	local -n arr=$1
+	local file=$2
+
+	while IFS='=' read -r cfg value
+	do
+		if [[ -v arr[$cfg] ]]; then
+			echo "Error: $cfg is redefined by $file."
+			exit 1
+		fi
+
+		arr[$cfg]=$value
+	done < <(sed -E 's/^# (CONFIG_.+) is not set$/\1=n/; /^\#/d; /^$/d' "$file")
+}
+
+# Figure out all valid options
+# allconfig doesn't contain all config, since Kconfig seems to omit
+# some implicit options like CONFIG_DEBUG_INFO. This is the best I can come
+# up with.
+declare -A allconfig
+make allyesconfig > /dev/null
+read_config allconfig .config
+
+# Use defconfig as the base
+declare -A config
+make defconfig
+read_config config .config
+
+# Remove all modules
+for cfg in "${!config[@]}"; do
+	if [[ "${config[$cfg]}" == "m" ]]; then
+		unset config[$cfg]
+	fi
+done
+
+# Merge configuration snippets
+declare -A overrides
+for file in "$dir/config" "$dir/config-$ARCH"; do
+	echo "Merging $file"
+	read_config overrides "$file"
+done
+
+for cfg in "${!overrides[@]}"; do
+	echo "$cfg=${overrides[$cfg]}"
+	config[$cfg]="${overrides[$cfg]}"
+done
+
+rm .config
+for cfg in "${!config[@]}"; do
+	echo "$cfg=${config[$cfg]}" >> .config
+done
+
+# Add missing configuration options.
 make olddefconfig
+
+# Validate that all the options have the value we want.
+declare -A effective
+read_config effective .config
+
+status=0
+for cfg in "${!overrides[@]}"; do
+	if [[ ! -v effective[$cfg] ]]; then
+		if [[ ! -v allconfig[$cfg] ]]; then
+			echo "Ignoring unrecognised option $cfg"
+			continue
+		fi
+
+		echo "Option $cfg: not present in config"
+		status=1
+		continue
+	fi
+
+	want="${overrides[$cfg]}"
+	have="${effective[$cfg]}"
+	case "$want" in
+		y|n|m)
+			if [[ "$have" != "$want" ]]; then
+				echo "Option $cfg: expected '$want', found '$have'"
+				status=1
+			fi
+			;;
+
+		*)
+			echo "Option $cfg: don't know how to handle '$want'"
+			status=1
+			;;
+	esac
+done
+
+exit $status

env.sh

@@ -2,10 +2,16 @@
 
 if [ "$TARGETPLATFORM" = "linux/amd64" ]; then
 	ARCH=x86_64
-	CROSS_COMPILE="ccache x86_64-linux-gnu-"
+	CROSS_COMPILE="x86_64-linux-gnu-"
 elif [ "$TARGETPLATFORM" = "linux/arm64" ]; then
-	ARCH=arm64 CROSS_COMPILE="ccache aarch64-linux-gnu-"
+	ARCH=arm64
+	CROSS_COMPILE="aarch64-linux-gnu-"
 else
 	echo "Unsupported target platform"; exit 1;
 fi
+
+if command -v ccache > /dev/null; then
+	CROSS_COMPILE="ccache $CROSS_COMPILE"
+fi
+
 export ARCH CROSS_COMPILE