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Linux/drivers/base/Kconfig

  1 menu "Generic Driver Options"
  2 
  3 config 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 
 18 config 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 
 28 config 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 
 47 config 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 
 62 config 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 
 71 config 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 
 80 config 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 
 88 config 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 
113 config 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 
140 config 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 
151 config FW_LOADER_USER_HELPER
152         bool
153 
154 config 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 
168 config WANT_DEV_COREDUMP
169         bool
170         help
171           Drivers should "select" this option if they desire to use the
172           device coredump mechanism.
173 
174 config 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 
187 config DEV_COREDUMP
188         bool
189         default y if WANT_DEV_COREDUMP
190         depends on ALLOW_DEV_COREDUMP
191 
192 config 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 
203 config 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 
215 config SYS_HYPERVISOR
216         bool
217         default n
218 
219 config GENERIC_CPU_DEVICES
220         bool
221         default n
222 
223 config GENERIC_CPU_AUTOPROBE
224         bool
225 
226 config SOC_BUS
227         bool
228 
229 source "drivers/base/regmap/Kconfig"
230 
231 config DMA_SHARED_BUFFER
232         bool
233         default n
234         select ANON_INODES
235         help
236           This option enables the framework for buffer-sharing between
237           multiple drivers. A buffer is associated with a file using driver
238           APIs extension; the file's descriptor can then be passed on to other
239           driver.
240 
241 config FENCE_TRACE
242         bool "Enable verbose FENCE_TRACE messages"
243         depends on DMA_SHARED_BUFFER
244         help
245           Enable the FENCE_TRACE printks. This will add extra
246           spam to the console log, but will make it easier to diagnose
247           lockup related problems for dma-buffers shared across multiple
248           devices.
249 
250 config DMA_CMA
251         bool "DMA Contiguous Memory Allocator"
252         depends on HAVE_DMA_CONTIGUOUS && CMA
253         help
254           This enables the Contiguous Memory Allocator which allows drivers
255           to allocate big physically-contiguous blocks of memory for use with
256           hardware components that do not support I/O map nor scatter-gather.
257 
258           You can disable CMA by specifying "cma=0" on the kernel's command
259           line.
260 
261           For more information see <include/linux/dma-contiguous.h>.
262           If unsure, say "n".
263 
264 if  DMA_CMA
265 comment "Default contiguous memory area size:"
266 
267 config CMA_SIZE_MBYTES
268         int "Size in Mega Bytes"
269         depends on !CMA_SIZE_SEL_PERCENTAGE
270         default 16
271         help
272           Defines the size (in MiB) of the default memory area for Contiguous
273           Memory Allocator.
274 
275 config CMA_SIZE_PERCENTAGE
276         int "Percentage of total memory"
277         depends on !CMA_SIZE_SEL_MBYTES
278         default 10
279         help
280           Defines the size of the default memory area for Contiguous Memory
281           Allocator as a percentage of the total memory in the system.
282 
283 choice
284         prompt "Selected region size"
285         default CMA_SIZE_SEL_MBYTES
286 
287 config CMA_SIZE_SEL_MBYTES
288         bool "Use mega bytes value only"
289 
290 config CMA_SIZE_SEL_PERCENTAGE
291         bool "Use percentage value only"
292 
293 config CMA_SIZE_SEL_MIN
294         bool "Use lower value (minimum)"
295 
296 config CMA_SIZE_SEL_MAX
297         bool "Use higher value (maximum)"
298 
299 endchoice
300 
301 config CMA_ALIGNMENT
302         int "Maximum PAGE_SIZE order of alignment for contiguous buffers"
303         range 4 12
304         default 8
305         help
306           DMA mapping framework by default aligns all buffers to the smallest
307           PAGE_SIZE order which is greater than or equal to the requested buffer
308           size. This works well for buffers up to a few hundreds kilobytes, but
309           for larger buffers it just a memory waste. With this parameter you can
310           specify the maximum PAGE_SIZE order for contiguous buffers. Larger
311           buffers will be aligned only to this specified order. The order is
312           expressed as a power of two multiplied by the PAGE_SIZE.
313 
314           For example, if your system defaults to 4KiB pages, the order value
315           of 8 means that the buffers will be aligned up to 1MiB only.
316 
317           If unsure, leave the default value "8".
318 
319 endif
320 
321 endmenu

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