1 # SPDX-License-Identifier: GPL-2.0 2 menu "Generic Driver Options" 3 4 config AUXILIARY_BUS 5 bool 6 7 config UEVENT_HELPER 8 bool "Support for uevent helper" 9 help 10 The uevent helper program is forked by the kernel for 11 every uevent. 12 Before the switch to the netlink-based uevent source, this was 13 used to hook hotplug scripts into kernel device events. It 14 usually pointed to a shell script at /sbin/hotplug. 15 This should not be used today, because usual systems create 16 many events at bootup or device discovery in a very short time 17 frame. One forked process per event can create so many processes 18 that it creates a high system load, or on smaller systems 19 it is known to create out-of-memory situations during bootup. 20 21 config UEVENT_HELPER_PATH 22 string "path to uevent helper" 23 depends on UEVENT_HELPER 24 default "" 25 help 26 To disable user space helper program execution at by default 27 specify an empty string here. This setting can still be altered 28 via /proc/sys/kernel/hotplug or via /sys/kernel/uevent_helper 29 later at runtime. 30 31 config DEVTMPFS 32 bool "Maintain a devtmpfs filesystem to mount at /dev" 33 help 34 This creates a tmpfs/ramfs filesystem instance early at bootup. 35 In this filesystem, the kernel driver core maintains device 36 nodes with their default names and permissions for all 37 registered devices with an assigned major/minor number. 38 Userspace can modify the filesystem content as needed, add 39 symlinks, and apply needed permissions. 40 It provides a fully functional /dev directory, where usually 41 udev runs on top, managing permissions and adding meaningful 42 symlinks. 43 In very limited environments, it may provide a sufficient 44 functional /dev without any further help. It also allows simple 45 rescue systems, and reliably handles dynamic major/minor numbers. 46 47 Notice: if CONFIG_TMPFS isn't enabled, the simpler ramfs 48 file system will be used instead. 49 50 config DEVTMPFS_MOUNT 51 bool "Automount devtmpfs at /dev, after the kernel mounted the rootfs" 52 depends on DEVTMPFS 53 help 54 This will instruct the kernel to automatically mount the 55 devtmpfs filesystem at /dev, directly after the kernel has 56 mounted the root filesystem. The behavior can be overridden 57 with the commandline parameter: devtmpfs.mount=0|1. 58 This option does not affect initramfs based booting, here 59 the devtmpfs filesystem always needs to be mounted manually 60 after the rootfs is mounted. 61 With this option enabled, it allows to bring up a system in 62 rescue mode with init=/bin/sh, even when the /dev directory 63 on the rootfs is completely empty. 64 65 config DEVTMPFS_SAFE 66 bool "Use nosuid,noexec mount options on devtmpfs" 67 depends on DEVTMPFS 68 help 69 This instructs the kernel to include the MS_NOEXEC and MS_NOSUID mount 70 flags when mounting devtmpfs. 71 72 Notice: If enabled, things like /dev/mem cannot be mmapped 73 with the PROT_EXEC flag. This can break, for example, non-KMS 74 video drivers. 75 76 config STANDALONE 77 bool "Select only drivers that don't need compile-time external firmware" 78 default y 79 help 80 Select this option if you don't have magic firmware for drivers that 81 need it. 82 83 If unsure, say Y. 84 85 config PREVENT_FIRMWARE_BUILD 86 bool "Disable drivers features which enable custom firmware building" 87 default y 88 help 89 Say yes to disable driver features which enable building a custom 90 driver firmware at kernel build time. These drivers do not use the 91 kernel firmware API to load firmware (CONFIG_FW_LOADER), instead they 92 use their own custom loading mechanism. The required firmware is 93 usually shipped with the driver, building the driver firmware 94 should only be needed if you have an updated firmware source. 95 96 Firmware should not be being built as part of kernel, these days 97 you should always prevent this and say Y here. There are only two 98 old drivers which enable building of its firmware at kernel build 99 time: 100 101 o CONFIG_WANXL through CONFIG_WANXL_BUILD_FIRMWARE 102 o CONFIG_SCSI_AIC79XX through CONFIG_AIC79XX_BUILD_FIRMWARE 103 104 source "drivers/base/firmware_loader/Kconfig" 105 106 config WANT_DEV_COREDUMP 107 bool 108 help 109 Drivers should "select" this option if they desire to use the 110 device coredump mechanism. 111 112 config ALLOW_DEV_COREDUMP 113 bool "Allow device coredump" if EXPERT 114 default y 115 help 116 This option controls if the device coredump mechanism is available or 117 not; if disabled, the mechanism will be omitted even if drivers that 118 can use it are enabled. 119 Say 'N' for more sensitive systems or systems that don't want 120 to ever access the information to not have the code, nor keep any 121 data. 122 123 If unsure, say Y. 124 125 config DEV_COREDUMP 126 bool 127 default y if WANT_DEV_COREDUMP 128 depends on ALLOW_DEV_COREDUMP 129 130 config DEBUG_DRIVER 131 bool "Driver Core verbose debug messages" 132 depends on DEBUG_KERNEL 133 help 134 Say Y here if you want the Driver core to produce a bunch of 135 debug messages to the system log. Select this if you are having a 136 problem with the driver core and want to see more of what is 137 going on. 138 139 If you are unsure about this, say N here. 140 141 config DEBUG_DEVRES 142 bool "Managed device resources verbose debug messages" 143 depends on DEBUG_KERNEL 144 help 145 This option enables kernel parameter devres.log. If set to 146 non-zero, devres debug messages are printed. Select this if 147 you are having a problem with devres or want to debug 148 resource management for a managed device. devres.log can be 149 switched on and off from sysfs node. 150 151 If you are unsure about this, Say N here. 152 153 config DEBUG_TEST_DRIVER_REMOVE 154 bool "Test driver remove calls during probe (UNSTABLE)" 155 depends on DEBUG_KERNEL 156 help 157 Say Y here if you want the Driver core to test driver remove functions 158 by calling probe, remove, probe. This tests the remove path without 159 having to unbind the driver or unload the driver module. 160 161 This option is expected to find errors and may render your system 162 unusable. You should say N here unless you are explicitly looking to 163 test this functionality. 164 165 config PM_QOS_KUNIT_TEST 166 bool "KUnit Test for PM QoS features" if !KUNIT_ALL_TESTS 167 depends on KUNIT=y 168 default KUNIT_ALL_TESTS 169 170 config HMEM_REPORTING 171 bool 172 default n 173 depends on NUMA 174 help 175 Enable reporting for heterogeneous memory access attributes under 176 their non-uniform memory nodes. 177 178 source "drivers/base/test/Kconfig" 179 180 config SYS_HYPERVISOR 181 bool 182 default n 183 184 config GENERIC_CPU_DEVICES 185 bool 186 default n 187 188 config GENERIC_CPU_AUTOPROBE 189 bool 190 191 config GENERIC_CPU_VULNERABILITIES 192 bool 193 194 config SOC_BUS 195 bool 196 select GLOB 197 198 source "drivers/base/regmap/Kconfig" 199 200 config DMA_SHARED_BUFFER 201 bool 202 default n 203 select IRQ_WORK 204 help 205 This option enables the framework for buffer-sharing between 206 multiple drivers. A buffer is associated with a file using driver 207 APIs extension; the file's descriptor can then be passed on to other 208 driver. 209 210 config DMA_FENCE_TRACE 211 bool "Enable verbose DMA_FENCE_TRACE messages" 212 depends on DMA_SHARED_BUFFER 213 help 214 Enable the DMA_FENCE_TRACE printks. This will add extra 215 spam to the console log, but will make it easier to diagnose 216 lockup related problems for dma-buffers shared across multiple 217 devices. 218 219 config GENERIC_ARCH_TOPOLOGY 220 bool 221 help 222 Enable support for architectures common topology code: e.g., parsing 223 CPU capacity information from DT, usage of such information for 224 appropriate scaling, sysfs interface for reading capacity values at 225 runtime. 226 227 config GENERIC_ARCH_NUMA 228 bool 229 select NUMA_MEMBLKS 230 help 231 Enable support for generic NUMA implementation. Currently, RISC-V 232 and ARM64 use it. 233 234 config FW_DEVLINK_SYNC_STATE_TIMEOUT 235 bool "sync_state() behavior defaults to timeout instead of strict" 236 help 237 This is build time equivalent of adding kernel command line parameter 238 "fw_devlink.sync_state=timeout". Give up waiting on consumers and 239 call sync_state() on any devices that haven't yet received their 240 sync_state() calls after deferred_probe_timeout has expired or by 241 late_initcall() if !CONFIG_MODULES. You should almost always want to 242 select N here unless you have already successfully tested with the 243 command line option on every system/board your kernel is expected to 244 work on. 245 246 endmenu 247