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