Move build-buildroot linux configs to build-linux.

Needs a lot of testing, and need to cleanup readme, but seems to work.

linux_config/buildroot-aarch64

@@ -0,0 +1,98 @@
+CONFIG_SYSVIPC=y
+CONFIG_POSIX_MQUEUE=y
+CONFIG_NO_HZ_IDLE=y
+CONFIG_HIGH_RES_TIMERS=y
+CONFIG_TASKSTATS=y
+CONFIG_IKCONFIG=y
+CONFIG_IKCONFIG_PROC=y
+CONFIG_SCHED_AUTOGROUP=y
+CONFIG_BLK_DEV_INITRD=y
+CONFIG_KALLSYMS_ALL=y
+CONFIG_PROFILING=y
+CONFIG_MODULES=y
+CONFIG_MODULE_UNLOAD=y
+CONFIG_MODVERSIONS=y
+CONFIG_MODULE_SRCVERSION_ALL=y
+CONFIG_BLK_DEV_BSGLIB=y
+CONFIG_ARCH_VEXPRESS=y
+CONFIG_PCI=y
+CONFIG_PCI_HOST_GENERIC=y
+CONFIG_TRANSPARENT_HUGEPAGE=y
+CONFIG_BINFMT_MISC=y
+CONFIG_COMPAT=y
+CONFIG_NET=y
+CONFIG_PACKET=y
+CONFIG_PACKET_DIAG=y
+CONFIG_UNIX=y
+CONFIG_NET_KEY=y
+CONFIG_INET=y
+CONFIG_IP_MULTICAST=y
+CONFIG_IP_ADVANCED_ROUTER=y
+CONFIG_BRIDGE=m
+CONFIG_NET_SCHED=y
+CONFIG_VSOCKETS=y
+CONFIG_NET_9P=y
+CONFIG_NET_9P_VIRTIO=y
+CONFIG_NET_9P_DEBUG=y
+CONFIG_DEVTMPFS=y
+CONFIG_DEVTMPFS_MOUNT=y
+CONFIG_CONNECTOR=y
+CONFIG_VIRTIO_BLK=y
+CONFIG_DUMMY_IRQ=m
+CONFIG_BLK_DEV_SD=y
+CONFIG_CHR_DEV_SG=y
+CONFIG_SCSI_CONSTANTS=y
+CONFIG_SCSI_LOGGING=y
+CONFIG_SCSI_SCAN_ASYNC=y
+CONFIG_SCSI_VIRTIO=y
+CONFIG_ATA=y
+CONFIG_ATA_PIIX=y
+CONFIG_NETDEVICES=y
+CONFIG_DUMMY=y
+CONFIG_MACVLAN=y
+CONFIG_VIRTIO_NET=y
+CONFIG_NLMON=y
+CONFIG_8139CP=y
+# CONFIG_INPUT_MOUSE is not set
+CONFIG_VT_HW_CONSOLE_BINDING=y
+CONFIG_SERIAL_AMBA_PL011=y
+CONFIG_SERIAL_AMBA_PL011_CONSOLE=y
+CONFIG_VIRTIO_CONSOLE=y
+CONFIG_HW_RANDOM=y
+CONFIG_HW_RANDOM_VIRTIO=y
+CONFIG_FB=y
+CONFIG_LOGO=y
+CONFIG_RTC_CLASS=y
+CONFIG_UIO=m
+CONFIG_UIO_PDRV_GENIRQ=m
+CONFIG_UIO_DMEM_GENIRQ=m
+CONFIG_UIO_PCI_GENERIC=m
+CONFIG_VIRTIO_PCI=y
+CONFIG_VIRTIO_MMIO=y
+CONFIG_VIRTIO_MMIO_CMDLINE_DEVICES=y
+CONFIG_MAILBOX=y
+CONFIG_PL320_MBOX=y
+CONFIG_EXT4_FS=y
+CONFIG_OVERLAY_FS=y
+CONFIG_TMPFS=y
+CONFIG_TMPFS_POSIX_ACL=y
+CONFIG_CONFIGFS_FS=y
+CONFIG_SQUASHFS=y
+CONFIG_9P_FS=y
+CONFIG_9P_FS_POSIX_ACL=y
+CONFIG_9P_FS_SECURITY=y
+CONFIG_DYNAMIC_DEBUG=y
+CONFIG_DEBUG_INFO=y
+CONFIG_GDB_SCRIPTS=y
+CONFIG_DEBUG_KERNEL=y
+CONFIG_IRQSOFF_TRACER=y
+CONFIG_SCHED_TRACER=y
+CONFIG_HWLAT_TRACER=y
+CONFIG_FTRACE_SYSCALLS=y
+CONFIG_STACK_TRACER=y
+CONFIG_FUNCTION_PROFILER=y
+CONFIG_KGDB=y
+CONFIG_KGDB_TESTS=y
+CONFIG_KGDB_KDB=y
+CONFIG_KDB_KEYBOARD=y
+# CONFIG_STRICT_DEVMEM is not set

linux_config/buildroot-arm

@@ -0,0 +1,180 @@
+# CONFIG_LOCALVERSION_AUTO is not set
+CONFIG_SYSVIPC=y
+CONFIG_IKCONFIG=y
+CONFIG_IKCONFIG_PROC=y
+CONFIG_LOG_BUF_SHIFT=14
+CONFIG_CGROUPS=y
+CONFIG_CPUSETS=y
+# CONFIG_UTS_NS is not set
+# CONFIG_IPC_NS is not set
+# CONFIG_PID_NS is not set
+# CONFIG_NET_NS is not set
+CONFIG_BLK_DEV_INITRD=y
+CONFIG_KALLSYMS_ALL=y
+CONFIG_PROFILING=y
+CONFIG_OPROFILE=y
+CONFIG_MODULES=y
+CONFIG_MODULE_UNLOAD=y
+CONFIG_MODVERSIONS=y
+CONFIG_MODULE_SRCVERSION_ALL=y
+# CONFIG_LBDAF is not set
+# CONFIG_BLK_DEV_BSG is not set
+# CONFIG_IOSCHED_DEADLINE is not set
+# CONFIG_IOSCHED_CFQ is not set
+CONFIG_ARCH_VEXPRESS=y
+CONFIG_ARCH_VEXPRESS_DCSCB=y
+CONFIG_ARCH_VEXPRESS_TC2_PM=y
+CONFIG_PCI=y
+CONFIG_PCI_HOST_GENERIC=y
+CONFIG_SMP=y
+CONFIG_HAVE_ARM_ARCH_TIMER=y
+CONFIG_MCPM=y
+CONFIG_VMSPLIT_2G=y
+CONFIG_NR_CPUS=8
+CONFIG_ARM_PSCI=y
+CONFIG_CMA=y
+CONFIG_ZBOOT_ROM_TEXT=0x0
+CONFIG_ZBOOT_ROM_BSS=0x0
+CONFIG_CMDLINE="console=ttyAMA0"
+CONFIG_CPU_IDLE=y
+CONFIG_VFP=y
+CONFIG_NEON=y
+# CONFIG_CORE_DUMP_DEFAULT_ELF_HEADERS is not set
+CONFIG_NET=y
+CONFIG_PACKET=y
+CONFIG_UNIX=y
+CONFIG_INET=y
+CONFIG_IP_PNP=y
+CONFIG_IP_PNP_DHCP=y
+CONFIG_IP_PNP_BOOTP=y
+# CONFIG_IPV6 is not set
+# CONFIG_WIRELESS is not set
+CONFIG_NET_9P=y
+CONFIG_NET_9P_VIRTIO=y
+CONFIG_NET_9P_DEBUG=y
+CONFIG_UEVENT_HELPER_PATH="/sbin/hotplug"
+CONFIG_DEVTMPFS=y
+CONFIG_DEVTMPFS_MOUNT=y
+CONFIG_CONNECTOR=y
+CONFIG_MTD=y
+CONFIG_MTD_CMDLINE_PARTS=y
+CONFIG_MTD_BLOCK=y
+CONFIG_MTD_CFI=y
+CONFIG_MTD_CFI_INTELEXT=y
+CONFIG_MTD_CFI_AMDSTD=y
+CONFIG_MTD_PHYSMAP=y
+CONFIG_MTD_PHYSMAP_OF=y
+CONFIG_MTD_PLATRAM=y
+CONFIG_MTD_UBI=y
+CONFIG_VIRTIO_BLK=y
+CONFIG_DUMMY_IRQ=m
+# CONFIG_SCSI_PROC_FS is not set
+CONFIG_BLK_DEV_SD=y
+CONFIG_SCSI_VIRTIO=y
+CONFIG_ATA=y
+# CONFIG_SATA_PMP is not set
+CONFIG_ATA_PIIX=y
+CONFIG_NETDEVICES=y
+CONFIG_VIRTIO_NET=y
+CONFIG_8139CP=y
+CONFIG_SMC91X=y
+CONFIG_SMSC911X=y
+# CONFIG_WLAN is not set
+CONFIG_INPUT_EVDEV=y
+# CONFIG_INPUT_MOUSE is not set
+# CONFIG_SERIO_SERPORT is not set
+CONFIG_SERIO_AMBAKMI=y
+CONFIG_LEGACY_PTY_COUNT=16
+CONFIG_SERIAL_AMBA_PL011=y
+CONFIG_SERIAL_AMBA_PL011_CONSOLE=y
+CONFIG_VIRTIO_CONSOLE=y
+CONFIG_HW_RANDOM=y
+CONFIG_HW_RANDOM_VIRTIO=y
+CONFIG_I2C=y
+CONFIG_I2C_VERSATILE=y
+CONFIG_SENSORS_VEXPRESS=y
+CONFIG_REGULATOR_VEXPRESS=y
+CONFIG_FB=y
+CONFIG_FB_ARMCLCD=y
+CONFIG_FRAMEBUFFER_CONSOLE=y
+CONFIG_FRAMEBUFFER_CONSOLE_ROTATION=y
+CONFIG_LOGO=y
+# CONFIG_LOGO_LINUX_MONO is not set
+# CONFIG_LOGO_LINUX_VGA16 is not set
+CONFIG_SOUND=y
+CONFIG_SND=y
+# CONFIG_SND_DRIVERS is not set
+CONFIG_SND_ARMAACI=y
+CONFIG_HID_DRAGONRISE=y
+CONFIG_HID_GYRATION=y
+CONFIG_HID_TWINHAN=y
+CONFIG_HID_NTRIG=y
+CONFIG_HID_PANTHERLORD=y
+CONFIG_HID_PETALYNX=y
+CONFIG_HID_SAMSUNG=y
+CONFIG_HID_SONY=y
+CONFIG_HID_SUNPLUS=y
+CONFIG_HID_GREENASIA=y
+CONFIG_HID_SMARTJOYPLUS=y
+CONFIG_HID_TOPSEED=y
+CONFIG_HID_THRUSTMASTER=y
+CONFIG_HID_ZEROPLUS=y
+CONFIG_USB=y
+CONFIG_USB_ANNOUNCE_NEW_DEVICES=y
+CONFIG_USB_MON=y
+CONFIG_USB_STORAGE=y
+CONFIG_USB_ISP1760=y
+CONFIG_MMC=y
+CONFIG_MMC_ARMMMCI=y
+CONFIG_NEW_LEDS=y
+CONFIG_LEDS_CLASS=y
+CONFIG_LEDS_GPIO=y
+CONFIG_LEDS_TRIGGERS=y
+CONFIG_LEDS_TRIGGER_HEARTBEAT=y
+CONFIG_LEDS_TRIGGER_CPU=y
+CONFIG_RTC_CLASS=y
+CONFIG_RTC_DRV_PL031=y
+CONFIG_UIO=m
+CONFIG_UIO_PDRV_GENIRQ=m
+CONFIG_UIO_DMEM_GENIRQ=m
+CONFIG_UIO_PCI_GENERIC=m
+CONFIG_VIRTIO_PCI=y
+CONFIG_VIRTIO_BALLOON=y
+CONFIG_VIRTIO_MMIO=y
+CONFIG_VIRTIO_MMIO_CMDLINE_DEVICES=y
+CONFIG_EXT2_FS=y
+CONFIG_EXT3_FS=y
+CONFIG_OVERLAY_FS=y
+CONFIG_VFAT_FS=y
+CONFIG_TMPFS=y
+CONFIG_CONFIGFS_FS=y
+CONFIG_JFFS2_FS=y
+CONFIG_UBIFS_FS=y
+CONFIG_CRAMFS=y
+CONFIG_SQUASHFS=y
+CONFIG_SQUASHFS_LZO=y
+CONFIG_NFS_FS=y
+CONFIG_ROOT_NFS=y
+CONFIG_9P_FS=y
+CONFIG_9P_FS_POSIX_ACL=y
+CONFIG_9P_FS_SECURITY=y
+CONFIG_NLS_CODEPAGE_437=y
+CONFIG_NLS_ISO8859_1=y
+CONFIG_DYNAMIC_DEBUG=y
+CONFIG_DEBUG_INFO=y
+CONFIG_GDB_SCRIPTS=y
+CONFIG_DEBUG_KERNEL=y
+CONFIG_DETECT_HUNG_TASK=y
+# CONFIG_SCHED_DEBUG is not set
+CONFIG_IRQSOFF_TRACER=y
+CONFIG_SCHED_TRACER=y
+CONFIG_HWLAT_TRACER=y
+CONFIG_FTRACE_SYSCALLS=y
+CONFIG_STACK_TRACER=y
+CONFIG_FUNCTION_PROFILER=y
+CONFIG_KGDB=y
+CONFIG_KGDB_TESTS=y
+CONFIG_KGDB_KDB=y
+CONFIG_KDB_KEYBOARD=y
+CONFIG_DEBUG_USER=y
+# CONFIG_CRYPTO_HW is not set

linux_config/buildroot-x86_64

@@ -0,0 +1,93 @@
+CONFIG_SYSVIPC=y
+CONFIG_IKCONFIG=y
+CONFIG_IKCONFIG_PROC=y
+CONFIG_CGROUPS=y
+CONFIG_BLK_DEV_INITRD=y
+CONFIG_KALLSYMS_ALL=y
+CONFIG_MODULES=y
+CONFIG_MODULE_UNLOAD=y
+CONFIG_MODVERSIONS=y
+CONFIG_MODULE_SRCVERSION_ALL=y
+CONFIG_SMP=y
+CONFIG_HYPERVISOR_GUEST=y
+CONFIG_PARAVIRT=y
+CONFIG_NET=y
+CONFIG_PACKET=y
+CONFIG_UNIX=y
+CONFIG_INET=y
+# CONFIG_WIRELESS is not set
+CONFIG_NET_9P=y
+CONFIG_NET_9P_VIRTIO=y
+CONFIG_NET_9P_DEBUG=y
+CONFIG_DEVTMPFS=y
+CONFIG_DEVTMPFS_MOUNT=y
+CONFIG_CONNECTOR=y
+CONFIG_VIRTIO_BLK=y
+CONFIG_DUMMY_IRQ=m
+CONFIG_BLK_DEV_SD=y
+CONFIG_SCSI_VIRTIO=y
+CONFIG_ATA=y
+CONFIG_ATA_PIIX=y
+CONFIG_NETDEVICES=y
+CONFIG_VIRTIO_NET=y
+CONFIG_NE2K_PCI=y
+CONFIG_8139CP=y
+# CONFIG_WLAN is not set
+CONFIG_INPUT_EVDEV=y
+# CONFIG_INPUT_MOUSE is not set
+CONFIG_SERIAL_8250=y
+CONFIG_SERIAL_8250_CONSOLE=y
+CONFIG_VIRTIO_CONSOLE=y
+CONFIG_HW_RANDOM_VIRTIO=m
+CONFIG_DRM=y
+CONFIG_DRM_QXL=y
+CONFIG_DRM_BOCHS=y
+CONFIG_DRM_VIRTIO_GPU=y
+CONFIG_FRAMEBUFFER_CONSOLE_ROTATION=y
+CONFIG_LOGO=y
+CONFIG_SOUND=y
+CONFIG_SND=y
+CONFIG_SND_HDA_INTEL=y
+CONFIG_SND_HDA_GENERIC=y
+CONFIG_USB=y
+CONFIG_USB_XHCI_HCD=y
+CONFIG_USB_EHCI_HCD=y
+CONFIG_USB_UHCI_HCD=y
+CONFIG_USB_STORAGE=y
+CONFIG_UIO=m
+CONFIG_UIO_PDRV_GENIRQ=m
+CONFIG_UIO_DMEM_GENIRQ=m
+CONFIG_UIO_PCI_GENERIC=m
+CONFIG_VIRTIO_PCI=y
+CONFIG_VIRTIO_BALLOON=y
+CONFIG_VIRTIO_INPUT=y
+CONFIG_VIRTIO_MMIO=y
+CONFIG_VIRTIO_MMIO_CMDLINE_DEVICES=y
+CONFIG_EXT4_FS=y
+CONFIG_AUTOFS4_FS=y
+CONFIG_OVERLAY_FS=y
+CONFIG_TMPFS=y
+CONFIG_TMPFS_POSIX_ACL=y
+CONFIG_CONFIGFS_FS=y
+CONFIG_SQUASHFS=y
+CONFIG_9P_FS=y
+CONFIG_9P_FS_POSIX_ACL=y
+CONFIG_9P_FS_SECURITY=y
+CONFIG_DYNAMIC_DEBUG=y
+CONFIG_DEBUG_INFO=y
+CONFIG_GDB_SCRIPTS=y
+CONFIG_DEBUG_KERNEL=y
+CONFIG_IRQSOFF_TRACER=y
+CONFIG_SCHED_TRACER=y
+CONFIG_HWLAT_TRACER=y
+CONFIG_FTRACE_SYSCALLS=y
+CONFIG_STACK_TRACER=y
+CONFIG_FUNCTION_PROFILER=y
+CONFIG_KGDB=y
+CONFIG_KGDB_TESTS=y
+CONFIG_KGDB_LOW_LEVEL_TRAP=y
+CONFIG_KGDB_KDB=y
+CONFIG_KDB_KEYBOARD=y
+# CONFIG_STRICT_DEVMEM is not set
+CONFIG_X86_PTDUMP=y
+CONFIG_UNWINDER_FRAME_POINTER=y

linux_config/default

@@ -0,0 +1,123 @@
+# Misc.
+CONFIG_BLK_DEV_INITRD=y
+CONFIG_DYNAMIC_DEBUG=y
+CONFIG_MODULE_SRCVERSION_ALL=y
+# CONFIG_STRICT_DEVMEM is not set
+
+# Filesystems.
+CONFIG_DEBUG_FS=y
+CONFIG_OVERLAY_FS=y
+CONFIG_SQUASHFS=y
+
+# GDB debugging.
+CONFIG_DEBUG_INFO=y
+CONFIG_DEBUG_KERNEL=y
+CONFIG_GDB_SCRIPTS=y
+
+# KGDB
+CONFIG_CONSOLE_POLL=y
+CONFIG_KDB_CONTINUE_CATASTROPHIC=0
+CONFIG_KDB_DEFAULT_ENABLE=0x1
+CONFIG_KDB_KEYBOARD=y
+CONFIG_KGDB=y
+CONFIG_KGDB_KDB=y
+CONFIG_KGDB_LOW_LEVEL_TRAP=y
+CONFIG_KGDB_SERIAL_CONSOLE=y
+CONFIG_KGDB_TESTS=y
+# CONFIG_KGDB_TESTS_ON_BOOT is not set
+CONFIG_MAGIC_SYSRQ=y
+CONFIG_MAGIC_SYSRQ_DEFAULT_ENABLE=0x1
+# CONFIG_SERIAL_KGDB_NMI is not set
+
+# Non-static variables show up on /proc/kallsyms
+# https://stackoverflow.com/questions/20196636/does-kallsyms-have-all-the-symbol-of-kernel-functions/44614878#44614878
+CONFIG_KALLSYMS_ALL=y
+
+# /proc/config.gz
+CONFIG_IKCONFIG=y
+CONFIG_IKCONFIG_PROC=y
+
+# TODO make example.
+# This seems to allow userspace to create arbitrary configuration trees,
+# which kernel modules can then read and interpret.
+CONFIG_CONFIGFS_FS=y
+
+# Module.symvers in kernel tree and modules tree contains CRC of signatures.
+# TODO: I think the CRC are stored in the built kernel and module, and checked
+# at insmod, but bgrep did not find it in kernel image.
+# Does not show in /proc/kallyms either.
+CONFIG_MODVERSIONS=y
+
+# ftrace
+CONFIG_DYNAMIC_FTRACE=y
+CONFIG_FTRACE=y
+CONFIG_FTRACE_SYSCALLS=y
+CONFIG_FUNCTION_GRAPH_TRACER=y
+CONFIG_FUNCTION_PROFILER=y
+CONFIG_FUNCTION_TRACER=y
+CONFIG_HWLAT_TRACER=y
+CONFIG_IRQSOFF_TRACER=y
+CONFIG_SCHED_TRACER=y
+CONFIG_STACK_TRACER=y
+CONFIG_TRACER_SNAPSHOT=y
+
+# Process tracing.
+CONFIG_CONNECTOR=y
+CONFIG_PROC_EVENTS=y
+
+# 9P
+CONFIG_9P_FS=y
+CONFIG_9P_FS_POSIX_ACL=y
+CONFIG_9P_FS_SECURITY=y
+CONFIG_NETWORK_FILESYSTEMS=y
+CONFIG_NET_9P=y
+CONFIG_NET_9P_DEBUG=y
+CONFIG_NET_9P_VIRTIO=y
+# 9P needed for ARM. Not fully minimized, but so be it.
+CONFIG_PCI=y
+CONFIG_PCI_HOST_COMMON=y
+CONFIG_PCI_HOST_GENERIC=y
+CONFIG_VIRTIO_PCI=y
+CONFIG_VIRTIO_BLK=y
+
+# Misc
+CONFIG_DUMMY_IRQ=m
+CONFIG_FRAMEBUFFER_CONSOLE_ROTATION=y
+# Requirement for LOGO.
+CONFIG_FB=y
+CONFIG_LOGO=y
+
+## Networking
+
+# If given, we can use QEMU 2.9.0 default x86 networking without any -net or -netdev options,
+# since E1000 is the default networking device as mentioned at:
+# https://en.wikibooks.org/w/index.php?title=QEMU/Networking&oldid=3268753
+#CONFIG_E1000=y
+
+## x86
+
+# https://stackoverflow.com/questions/20069620/print-kernels-page-table-entries
+# cat /sys/kernel/debug/kernel_page_tables
+CONFIG_X86_PTDUMP=y
+
+## UIO
+
+# All other UIO depend on this module.
+CONFIG_UIO=m
+
+# Generic platform devices.
+# https://yurovsky.github.io/2014/10/10/linux-uio-gpio-interrupt/
+CONFIG_UIO_DMEM_GENIRQ=m
+CONFIG_UIO_PDRV_GENIRQ=m
+
+# https://github.com/rumpkernel/wiki/wiki/Howto:-Accessing-PCI-devices-from-userspace
+# /sys/class/uio/
+# /sys/class/uio/uio0
+CONFIG_UIO_PCI_GENERIC=m
+
+## ARM
+
+CONFIG_ARM64_PTDUMP=y
+
+# For record and replay.
+CONFIG_8139CP=y

linux_config/display

@@ -0,0 +1,9 @@
+CONFIG_DRM=y
+
+## QEMU
+CONFIG_DRM_VIRTIO_GPU=y
+
+## gem5
+CONFIG_DRM_HDLCD=y
+# Only present in the gem5 fork.
+CONFIG_DRM_VIRT_ENCODER=y

linux_config/gpio

@@ -0,0 +1,4 @@
+CONFIG_ARM_AMBA=y
+CONFIG_GPIOLIB=y
+CONFIG_GPIO_SYSFS=y
+CONFIG_GPIO_PL061=y

linux_config/leds

@@ -0,0 +1,12 @@
+CONFIG_LEDS_CLASS=y
+CONFIG_LEDS_CLASS_FLASH=y
+CONFIG_LEDS_SYSCON=y
+CONFIG_LEDS_TRIGGERS=y
+CONFIG_LEDS_TRIGGER_BACKLIGHT=y
+CONFIG_LEDS_TRIGGER_CPU=y
+CONFIG_LEDS_TRIGGER_DEFAULT_ON=y
+CONFIG_LEDS_TRIGGER_GPIO=y
+CONFIG_LEDS_TRIGGER_HEARTBEAT=y
+CONFIG_LEDS_TRIGGER_ONESHOT=y
+CONFIG_LEDS_TRIGGER_TIMER=y
+CONFIG_NEW_LEDS=y

linux_config/min

@@ -0,0 +1,25 @@
+# This file contains only configs which are required to boot all configurations and get a shell.
+
+## gem5 x86
+
+# CONFIG_INPUT_MOUSE is not set
+# CONFIG_INPUT_MOUSEDEV_PSAUX is not set
+
+## qemu aarch64
+
+# For some reason not selected by the Buildroot kernel config by default as it was for arm,
+# and pci modules fail to build. Not that we have PCI working on ARM anyways.
+CONFIG_PCI=y
+
+## gem5 aarch64
+
+# Minimal options required to run gem5 aarch64 in addition to QEMU's aarch64 setup.
+# Doing such a minimal boot made the gem5 boot 3x faster on the P51, which is awesome.
+CONFIG_ATA_PIIX=y
+CONFIG_PCI_HOST_GENERIC=y
+
+## qemu aarch64 ext2
+
+# Also requires gem5 aarch64 options.
+# Not needed for initrd / initramfs.
+CONFIG_VIRTIO_PCI=y