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 The kernel source tree includes a number of firmware 'blobs' 95 that are used by various drivers. The recommended way to 96 use these is to run "make firmware_install", which, after 97 converting ihex files to binary, copies all of the needed 98 binary files in firmware/ to /lib/firmware/ on your system so 99 that they can be loaded by userspace helpers on request. 100 101 Enabling this option will build each required firmware blob 102 into the kernel directly, where request_firmware() will find 103 them without having to call out to userspace. This may be 104 useful if your root file system requires a device that uses 105 such firmware and do not wish to use an initrd. 106 107 This single option controls the inclusion of firmware for 108 every driver that uses request_firmware() and ships its 109 firmware in the kernel source tree, which avoids a 110 proliferation of 'Include firmware for xxx device' options. 111 112 Say 'N' and let firmware be loaded from userspace. 113 114config EXTRA_FIRMWARE 115 string "External firmware blobs to build into the kernel binary" 116 depends on FW_LOADER 117 help 118 This option allows firmware to be built into the kernel for the case 119 where the user either cannot or doesn't want to provide it from 120 userspace at runtime (for example, when the firmware in question is 121 required for accessing the boot device, and the user doesn't want to 122 use an initrd). 123 124 This option is a string and takes the (space-separated) names of the 125 firmware files -- the same names that appear in MODULE_FIRMWARE() 126 and request_firmware() in the source. These files should exist under 127 the directory specified by the EXTRA_FIRMWARE_DIR option, which is 128 by default the firmware subdirectory of the kernel source tree. 129 130 For example, you might set CONFIG_EXTRA_FIRMWARE="usb8388.bin", copy 131 the usb8388.bin file into the firmware directory, and build the kernel. 132 Then any request_firmware("usb8388.bin") will be satisfied internally 133 without needing to call out to userspace. 134 135 WARNING: If you include additional firmware files into your binary 136 kernel image that are not available under the terms of the GPL, 137 then it may be a violation of the GPL to distribute the resulting 138 image since it combines both GPL and non-GPL work. You should 139 consult a lawyer of your own before distributing such an image. 140 141config EXTRA_FIRMWARE_DIR 142 string "Firmware blobs root directory" 143 depends on EXTRA_FIRMWARE != "" 144 default "/lib/firmware" 145 help 146 This option controls the directory in which the kernel build system 147 looks for the firmware files listed in the EXTRA_FIRMWARE option. 148 149config FW_LOADER_USER_HELPER 150 bool 151 152config FW_LOADER_USER_HELPER_FALLBACK 153 bool "Fallback user-helper invocation for firmware loading" 154 depends on FW_LOADER 155 select FW_LOADER_USER_HELPER 156 help 157 This option enables / disables the invocation of user-helper 158 (e.g. udev) for loading firmware files as a fallback after the 159 direct file loading in kernel fails. The user-mode helper is 160 no longer required unless you have a special firmware file that 161 resides in a non-standard path. Moreover, the udev support has 162 been deprecated upstream. 163 164 If you are unsure about this, say N here. 165 166config WANT_DEV_COREDUMP 167 bool 168 help 169 Drivers should "select" this option if they desire to use the 170 device coredump mechanism. 171 172config ALLOW_DEV_COREDUMP 173 bool "Allow device coredump" if EXPERT 174 default y 175 help 176 This option controls if the device coredump mechanism is available or 177 not; if disabled, the mechanism will be omitted even if drivers that 178 can use it are enabled. 179 Say 'N' for more sensitive systems or systems that don't want 180 to ever access the information to not have the code, nor keep any 181 data. 182 183 If unsure, say Y. 184 185config DEV_COREDUMP 186 bool 187 default y if WANT_DEV_COREDUMP 188 depends on ALLOW_DEV_COREDUMP 189 190config DEBUG_DRIVER 191 bool "Driver Core verbose debug messages" 192 depends on DEBUG_KERNEL 193 help 194 Say Y here if you want the Driver core to produce a bunch of 195 debug messages to the system log. Select this if you are having a 196 problem with the driver core and want to see more of what is 197 going on. 198 199 If you are unsure about this, say N here. 200 201config DEBUG_DEVRES 202 bool "Managed device resources verbose debug messages" 203 depends on DEBUG_KERNEL 204 help 205 This option enables kernel parameter devres.log. If set to 206 non-zero, devres debug messages are printed. Select this if 207 you are having a problem with devres or want to debug 208 resource management for a managed device. devres.log can be 209 switched on and off from sysfs node. 210 211 If you are unsure about this, Say N here. 212 213config DEBUG_TEST_DRIVER_REMOVE 214 bool "Test driver remove calls during probe (UNSTABLE)" 215 depends on DEBUG_KERNEL 216 help 217 Say Y here if you want the Driver core to test driver remove functions 218 by calling probe, remove, probe. This tests the remove path without 219 having to unbind the driver or unload the driver module. 220 221 This option is expected to find errors and may render your system 222 unusable. You should say N here unless you are explicitly looking to 223 test this functionality. 224 225source "drivers/base/test/Kconfig" 226 227config SYS_HYPERVISOR 228 bool 229 default n 230 231config GENERIC_CPU_DEVICES 232 bool 233 default n 234 235config GENERIC_CPU_AUTOPROBE 236 bool 237 238config GENERIC_CPU_VULNERABILITIES 239 bool 240 241config SOC_BUS 242 bool 243 select GLOB 244 245source "drivers/base/regmap/Kconfig" 246 247config DMA_SHARED_BUFFER 248 bool 249 default n 250 select ANON_INODES 251 help 252 This option enables the framework for buffer-sharing between 253 multiple drivers. A buffer is associated with a file using driver 254 APIs extension; the file's descriptor can then be passed on to other 255 driver. 256 257config DMA_FENCE_TRACE 258 bool "Enable verbose DMA_FENCE_TRACE messages" 259 depends on DMA_SHARED_BUFFER 260 help 261 Enable the DMA_FENCE_TRACE printks. This will add extra 262 spam to the console log, but will make it easier to diagnose 263 lockup related problems for dma-buffers shared across multiple 264 devices. 265 266config DMA_CMA 267 bool "DMA Contiguous Memory Allocator" 268 depends on HAVE_DMA_CONTIGUOUS && CMA 269 help 270 This enables the Contiguous Memory Allocator which allows drivers 271 to allocate big physically-contiguous blocks of memory for use with 272 hardware components that do not support I/O map nor scatter-gather. 273 274 You can disable CMA by specifying "cma=0" on the kernel's command 275 line. 276 277 For more information see <include/linux/dma-contiguous.h>. 278 If unsure, say "n". 279 280if DMA_CMA 281comment "Default contiguous memory area size:" 282 283config CMA_SIZE_MBYTES 284 int "Size in Mega Bytes" 285 depends on !CMA_SIZE_SEL_PERCENTAGE 286 default 0 if X86 287 default 16 288 help 289 Defines the size (in MiB) of the default memory area for Contiguous 290 Memory Allocator. If the size of 0 is selected, CMA is disabled by 291 default, but it can be enabled by passing cma=size[MG] to the kernel. 292 293 294config CMA_SIZE_PERCENTAGE 295 int "Percentage of total memory" 296 depends on !CMA_SIZE_SEL_MBYTES 297 default 0 if X86 298 default 10 299 help 300 Defines the size of the default memory area for Contiguous Memory 301 Allocator as a percentage of the total memory in the system. 302 If 0 percent is selected, CMA is disabled by default, but it can be 303 enabled by passing cma=size[MG] to the kernel. 304 305choice 306 prompt "Selected region size" 307 default CMA_SIZE_SEL_MBYTES 308 309config CMA_SIZE_SEL_MBYTES 310 bool "Use mega bytes value only" 311 312config CMA_SIZE_SEL_PERCENTAGE 313 bool "Use percentage value only" 314 315config CMA_SIZE_SEL_MIN 316 bool "Use lower value (minimum)" 317 318config CMA_SIZE_SEL_MAX 319 bool "Use higher value (maximum)" 320 321endchoice 322 323config CMA_ALIGNMENT 324 int "Maximum PAGE_SIZE order of alignment for contiguous buffers" 325 range 4 12 326 default 8 327 help 328 DMA mapping framework by default aligns all buffers to the smallest 329 PAGE_SIZE order which is greater than or equal to the requested buffer 330 size. This works well for buffers up to a few hundreds kilobytes, but 331 for larger buffers it just a memory waste. With this parameter you can 332 specify the maximum PAGE_SIZE order for contiguous buffers. Larger 333 buffers will be aligned only to this specified order. The order is 334 expressed as a power of two multiplied by the PAGE_SIZE. 335 336 For example, if your system defaults to 4KiB pages, the order value 337 of 8 means that the buffers will be aligned up to 1MiB only. 338 339 If unsure, leave the default value "8". 340 341endif 342 343config GENERIC_ARCH_TOPOLOGY 344 bool 345 help 346 Enable support for architectures common topology code: e.g., parsing 347 CPU capacity information from DT, usage of such information for 348 appropriate scaling, sysfs interface for changing capacity values at 349 runtime. 350 351endmenu 352