linux: enable PREEMPT_RT

This includes the real-time patch set and enables PREEMPT_RT.

linux-6.6.defconfig

@@ -4,7 +4,7 @@ CONFIG_SYSVIPC=y
 CONFIG_POSIX_MQUEUE=y
 CONFIG_NO_HZ=y
 CONFIG_HIGH_RES_TIMERS=y
-CONFIG_PREEMPT=y
+CONFIG_PREEMPT_RT=y
 CONFIG_MEMCG=y
 CONFIG_BLK_CGROUP=y
 CONFIG_CFS_BANDWIDTH=y
@@ -13,11 +13,13 @@ CONFIG_CGROUP_FREEZER=y
 CONFIG_CPUSETS=y
 CONFIG_CGROUP_DEVICE=y
 CONFIG_CGROUP_CPUACCT=y
+CONFIG_NAMESPACES=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_SCHED_AUTOGROUP=y
+CONFIG_EXPERT=y
 # CONFIG_PERF_EVENTS is not set
 CONFIG_PROFILING=y
 CONFIG_ARCH_BCM=y
@@ -350,9 +352,11 @@ CONFIG_REGULATOR_GPIO=y
 CONFIG_REGULATOR_RASPBERRYPI_TOUCHSCREEN_ATTINY=m
 CONFIG_REGULATOR_RASPBERRYPI_TOUCHSCREEN_V2=m
 CONFIG_MEDIA_SUPPORT=m
+CONFIG_MEDIA_SUPPORT_FILTER=y
 CONFIG_MEDIA_CAMERA_SUPPORT=y
 CONFIG_MEDIA_PLATFORM_SUPPORT=y
 CONFIG_MEDIA_USB_SUPPORT=y
+CONFIG_V4L_PLATFORM_DRIVERS=y
 CONFIG_VIDEO_BCM2835_UNICAM=m
 CONFIG_VIDEO_RASPBERRYPI_PISP_BE=m
 CONFIG_VIDEO_RP1_CFE=m
@@ -400,7 +404,6 @@ CONFIG_SND_BCM2708_SOC_HIFIBERRY_DAC=m
 CONFIG_SND_SIMPLE_CARD=m
 CONFIG_SND_AUDIO_GRAPH_CARD=m
 CONFIG_HIDRAW=y
-# CONFIG_HID_A4TECH is not set
 CONFIG_HID_APPLE=m
 CONFIG_HID_PID=y
 CONFIG_USB_HIDDEV=y
@@ -442,7 +445,6 @@ CONFIG_LEDS_TRIGGER_TIMER=y
 CONFIG_LEDS_TRIGGER_ONESHOT=y
 CONFIG_LEDS_TRIGGER_HEARTBEAT=y
 CONFIG_LEDS_TRIGGER_BACKLIGHT=y
-CONFIG_LEDS_TRIGGER_CPU=y
 CONFIG_LEDS_TRIGGER_DEFAULT_ON=y
 CONFIG_LEDS_TRIGGER_TRANSIENT=y
 CONFIG_LEDS_TRIGGER_INPUT=y

nerves_defconfig

@@ -29,7 +29,7 @@ BR2_ROOTFS_POST_IMAGE_SCRIPT="${NERVES_DEFCONFIG_DIR}/post-createfs.sh"
 BR2_LINUX_KERNEL=y
 BR2_LINUX_KERNEL_CUSTOM_TARBALL=y
 BR2_LINUX_KERNEL_CUSTOM_TARBALL_LOCATION="https://github.com/raspberrypi/linux/archive/refs/tags/stable_20241008.tar.gz"
-BR2_LINUX_KERNEL_PATCH="${NERVES_DEFCONFIG_DIR}/linux"
+BR2_LINUX_KERNEL_PATCH="http://cdn.kernel.org/pub/linux/kernel/projects/rt/6.6/patch-6.6.53-rt44.patch.gz ${NERVES_DEFCONFIG_DIR}/linux"
 BR2_LINUX_KERNEL_USE_CUSTOM_CONFIG=y
 BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE="${NERVES_DEFCONFIG_DIR}/linux-6.6.defconfig"
 BR2_LINUX_KERNEL_XZ=y