1# SPDX-License-Identifier: GPL-2.0 2menu "Generic Driver Options" 3 4config UEVENT_HELPER 5 bool "Support for uevent helper" 6 default y 7 help 8 The uevent helper program is forked by the kernel for 9 every uevent. 10 Before the switch to the netlink-based uevent source, this was 11 used to hook hotplug scripts into kernel device events. It 12 usually pointed to a shell script at /sbin/hotplug. 13 This should not be used today, because usual systems create 14 many events at bootup or device discovery in a very short time 15 frame. One forked process per event can create so many processes 16 that it creates a high system load, or on smaller systems 17 it is known to create out-of-memory situations during bootup. 18 19config UEVENT_HELPER_PATH 20 string "path to uevent helper" 21 depends on UEVENT_HELPER 22 default "" 23 help 24 To disable user space helper program execution at by default 25 specify an empty string here. This setting can still be altered 26 via /proc/sys/kernel/hotplug or via /sys/kernel/uevent_helper 27 later at runtime. 28 29config DEVTMPFS 30 bool "Maintain a devtmpfs filesystem to mount at /dev" 31 help 32 This creates a tmpfs/ramfs filesystem instance early at bootup. 33 In this filesystem, the kernel driver core maintains device 34 nodes with their default names and permissions for all 35 registered devices with an assigned major/minor number. 36 Userspace can modify the filesystem content as needed, add 37 symlinks, and apply needed permissions. 38 It provides a fully functional /dev directory, where usually 39 udev runs on top, managing permissions and adding meaningful 40 symlinks. 41 In very limited environments, it may provide a sufficient 42 functional /dev without any further help. It also allows simple 43 rescue systems, and reliably handles dynamic major/minor numbers. 44 45 Notice: if CONFIG_TMPFS isn't enabled, the simpler ramfs 46 file system will be used instead. 47 48config DEVTMPFS_MOUNT 49 bool "Automount devtmpfs at /dev, after the kernel mounted the rootfs" 50 depends on DEVTMPFS 51 help 52 This will instruct the kernel to automatically mount the 53 devtmpfs filesystem at /dev, directly after the kernel has 54 mounted the root filesystem. The behavior can be overridden 55 with the commandline parameter: devtmpfs.mount=0|1. 56 This option does not affect initramfs based booting, here 57 the devtmpfs filesystem always needs to be mounted manually 58 after the rootfs is mounted. 59 With this option enabled, it allows to bring up a system in 60 rescue mode with init=/bin/sh, even when the /dev directory 61 on the rootfs is completely empty. 62 63config STANDALONE 64 bool "Select only drivers that don't need compile-time external firmware" 65 default y 66 help 67 Select this option if you don't have magic firmware for drivers that 68 need it. 69 70 If unsure, say Y. 71 72config PREVENT_FIRMWARE_BUILD 73 bool "Prevent firmware from being built" 74 default y 75 help 76 Say yes to avoid building firmware. Firmware is usually shipped 77 with the driver and only when updating the firmware should a 78 rebuild be made. 79 If unsure, say Y here. 80 81config FW_LOADER 82 tristate "Userspace firmware loading support" if EXPERT 83 default y 84 ---help--- 85 This option is provided for the case where none of the in-tree modules 86 require userspace firmware loading support, but a module built 87 out-of-tree does. 88 89config FIRMWARE_IN_KERNEL 90 bool "Include in-kernel firmware blobs in kernel binary" 91 depends on FW_LOADER 92 default y 93 help 94 Various drivers in the kernel source tree may require firmware, 95 which is generally available in your distribution's linux-firmware 96 package. 97 98 The linux-firmware package should install firmware into 99 /lib/firmware/ on your system, so they can be loaded by userspace 100 helpers on request. 101 102 Enabling this option will build each required firmware blob 103 specified by EXTRA_FIRMWARE into the kernel directly, where 104 request_firmware() will find them without having to call out to 105 userspace. This may be useful if your root file system requires a 106 device that uses such firmware and you do not wish to use an 107 initrd. 108 109 This single option controls the inclusion of firmware for 110 every driver that uses request_firmware(), which avoids a 111 proliferation of 'Include firmware for xxx device' options. 112 113 Say 'N' and let firmware be loaded from userspace. 114 115config EXTRA_FIRMWARE 116 string "External firmware blobs to build into the kernel binary" 117 depends on FW_LOADER 118 help 119 This option allows firmware to be built into the kernel for the case 120 where the user either cannot or doesn't want to provide it from 121 userspace at runtime (for example, when the firmware in question is 122 required for accessing the boot device, and the user doesn't want to 123 use an initrd). 124 125 This option is a string and takes the (space-separated) names of the 126 firmware files -- the same names that appear in MODULE_FIRMWARE() 127 and request_firmware() in the source. These files should exist under 128 the directory specified by the EXTRA_FIRMWARE_DIR option, which is 129 by default the firmware subdirectory of the kernel source tree. 130 131 For example, you might set CONFIG_EXTRA_FIRMWARE="usb8388.bin", copy 132 the usb8388.bin file into the firmware directory, and build the kernel. 133 Then any request_firmware("usb8388.bin") will be satisfied internally 134 without needing to call out to userspace. 135 136 WARNING: If you include additional firmware files into your binary 137 kernel image that are not available under the terms of the GPL, 138 then it may be a violation of the GPL to distribute the resulting 139 image since it combines both GPL and non-GPL work. You should 140 consult a lawyer of your own before distributing such an image. 141 142config EXTRA_FIRMWARE_DIR 143 string "Firmware blobs root directory" 144 depends on EXTRA_FIRMWARE != "" 145 default "/lib/firmware" 146 help 147 This option controls the directory in which the kernel build system 148 looks for the firmware files listed in the EXTRA_FIRMWARE option. 149 150config FW_LOADER_USER_HELPER 151 bool 152 153config FW_LOADER_USER_HELPER_FALLBACK 154 bool "Fallback user-helper invocation for firmware loading" 155 depends on FW_LOADER 156 select FW_LOADER_USER_HELPER 157 help 158 This option enables / disables the invocation of user-helper 159 (e.g. udev) for loading firmware files as a fallback after the 160 direct file loading in kernel fails. The user-mode helper is 161 no longer required unless you have a special firmware file that 162 resides in a non-standard path. Moreover, the udev support has 163 been deprecated upstream. 164 165 If you are unsure about this, say N here. 166 167config WANT_DEV_COREDUMP 168 bool 169 help 170 Drivers should "select" this option if they desire to use the 171 device coredump mechanism. 172 173config ALLOW_DEV_COREDUMP 174 bool "Allow device coredump" if EXPERT 175 default y 176 help 177 This option controls if the device coredump mechanism is available or 178 not; if disabled, the mechanism will be omitted even if drivers that 179 can use it are enabled. 180 Say 'N' for more sensitive systems or systems that don't want 181 to ever access the information to not have the code, nor keep any 182 data. 183 184 If unsure, say Y. 185 186config DEV_COREDUMP 187 bool 188 default y if WANT_DEV_COREDUMP 189 depends on ALLOW_DEV_COREDUMP 190 191config DEBUG_DRIVER 192 bool "Driver Core verbose debug messages" 193 depends on DEBUG_KERNEL 194 help 195 Say Y here if you want the Driver core to produce a bunch of 196 debug messages to the system log. Select this if you are having a 197 problem with the driver core and want to see more of what is 198 going on. 199 200 If you are unsure about this, say N here. 201 202config DEBUG_DEVRES 203 bool "Managed device resources verbose debug messages" 204 depends on DEBUG_KERNEL 205 help 206 This option enables kernel parameter devres.log. If set to 207 non-zero, devres debug messages are printed. Select this if 208 you are having a problem with devres or want to debug 209 resource management for a managed device. devres.log can be 210 switched on and off from sysfs node. 211 212 If you are unsure about this, Say N here. 213 214config DEBUG_TEST_DRIVER_REMOVE 215 bool "Test driver remove calls during probe (UNSTABLE)" 216 depends on DEBUG_KERNEL 217 help 218 Say Y here if you want the Driver core to test driver remove functions 219 by calling probe, remove, probe. This tests the remove path without 220 having to unbind the driver or unload the driver module. 221 222 This option is expected to find errors and may render your system 223 unusable. You should say N here unless you are explicitly looking to 224 test this functionality. 225 226source "drivers/base/test/Kconfig" 227 228config SYS_HYPERVISOR 229 bool 230 default n 231 232config GENERIC_CPU_DEVICES 233 bool 234 default n 235 236config GENERIC_CPU_AUTOPROBE 237 bool 238 239config GENERIC_CPU_VULNERABILITIES 240 bool 241 242config SOC_BUS 243 bool 244 select GLOB 245 246source "drivers/base/regmap/Kconfig" 247 248config DMA_SHARED_BUFFER 249 bool 250 default n 251 select ANON_INODES 252 help 253 This option enables the framework for buffer-sharing between 254 multiple drivers. A buffer is associated with a file using driver 255 APIs extension; the file's descriptor can then be passed on to other 256 driver. 257 258config DMA_FENCE_TRACE 259 bool "Enable verbose DMA_FENCE_TRACE messages" 260 depends on DMA_SHARED_BUFFER 261 help 262 Enable the DMA_FENCE_TRACE printks. This will add extra 263 spam to the console log, but will make it easier to diagnose 264 lockup related problems for dma-buffers shared across multiple 265 devices. 266 267config DMA_CMA 268 bool "DMA Contiguous Memory Allocator" 269 depends on HAVE_DMA_CONTIGUOUS && CMA 270 help 271 This enables the Contiguous Memory Allocator which allows drivers 272 to allocate big physically-contiguous blocks of memory for use with 273 hardware components that do not support I/O map nor scatter-gather. 274 275 You can disable CMA by specifying "cma=0" on the kernel's command 276 line. 277 278 For more information see <include/linux/dma-contiguous.h>. 279 If unsure, say "n". 280 281if DMA_CMA 282comment "Default contiguous memory area size:" 283 284config CMA_SIZE_MBYTES 285 int "Size in Mega Bytes" 286 depends on !CMA_SIZE_SEL_PERCENTAGE 287 default 0 if X86 288 default 16 289 help 290 Defines the size (in MiB) of the default memory area for Contiguous 291 Memory Allocator. If the size of 0 is selected, CMA is disabled by 292 default, but it can be enabled by passing cma=size[MG] to the kernel. 293 294 295config CMA_SIZE_PERCENTAGE 296 int "Percentage of total memory" 297 depends on !CMA_SIZE_SEL_MBYTES 298 default 0 if X86 299 default 10 300 help 301 Defines the size of the default memory area for Contiguous Memory 302 Allocator as a percentage of the total memory in the system. 303 If 0 percent is selected, CMA is disabled by default, but it can be 304 enabled by passing cma=size[MG] to the kernel. 305 306choice 307 prompt "Selected region size" 308 default CMA_SIZE_SEL_MBYTES 309 310config CMA_SIZE_SEL_MBYTES 311 bool "Use mega bytes value only" 312 313config CMA_SIZE_SEL_PERCENTAGE 314 bool "Use percentage value only" 315 316config CMA_SIZE_SEL_MIN 317 bool "Use lower value (minimum)" 318 319config CMA_SIZE_SEL_MAX 320 bool "Use higher value (maximum)" 321 322endchoice 323 324config CMA_ALIGNMENT 325 int "Maximum PAGE_SIZE order of alignment for contiguous buffers" 326 range 4 12 327 default 8 328 help 329 DMA mapping framework by default aligns all buffers to the smallest 330 PAGE_SIZE order which is greater than or equal to the requested buffer 331 size. This works well for buffers up to a few hundreds kilobytes, but 332 for larger buffers it just a memory waste. With this parameter you can 333 specify the maximum PAGE_SIZE order for contiguous buffers. Larger 334 buffers will be aligned only to this specified order. The order is 335 expressed as a power of two multiplied by the PAGE_SIZE. 336 337 For example, if your system defaults to 4KiB pages, the order value 338 of 8 means that the buffers will be aligned up to 1MiB only. 339 340 If unsure, leave the default value "8". 341 342endif 343 344config GENERIC_ARCH_TOPOLOGY 345 bool 346 help 347 Enable support for architectures common topology code: e.g., parsing 348 CPU capacity information from DT, usage of such information for 349 appropriate scaling, sysfs interface for changing capacity values at 350 runtime. 351 352endmenu 353