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1# SPDX-License-Identifier: GPL-2.0
2menu "Generic Driver Options"
3
4config AUXILIARY_BUS
5 bool
6
7config 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
21config 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
31config 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
50config 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
65config 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
76config 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
85config 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
104source "drivers/base/firmware_loader/Kconfig"
105
106config WANT_DEV_COREDUMP
107 bool
108 help
109 Drivers should "select" this option if they desire to use the
110 device coredump mechanism.
111
112config 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
125config DEV_COREDUMP
126 bool
127 default y if WANT_DEV_COREDUMP
128 depends on ALLOW_DEV_COREDUMP
129
130config 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
141config 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
153config 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
165config 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
170config 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
178source "drivers/base/test/Kconfig"
179
180config SYS_HYPERVISOR
181 bool
182 default n
183
184config GENERIC_CPU_DEVICES
185 bool
186 default n
187
188config GENERIC_CPU_AUTOPROBE
189 bool
190
191config GENERIC_CPU_VULNERABILITIES
192 bool
193
194config SOC_BUS
195 bool
196 select GLOB
197
198source "drivers/base/regmap/Kconfig"
199
200config 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
210config 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
219config 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
227config GENERIC_ARCH_NUMA
228 bool
229 help
230 Enable support for generic NUMA implementation. Currently, RISC-V
231 and ARM64 use it.
232
233endmenu
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
342endmenu