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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 "Fallback user-helper invocation for firmware loading"
153         depends on FW_LOADER
154         default y
155         help
156           This option enables / disables the invocation of user-helper
157           (e.g. udev) for loading firmware files as a fallback after the
158           direct file loading in kernel fails.  The user-mode helper is
159           no longer required unless you have a special firmware file that
160           resides in a non-standard path.
161 
162 config DEBUG_DRIVER
163         bool "Driver Core verbose debug messages"
164         depends on DEBUG_KERNEL
165         help
166           Say Y here if you want the Driver core to produce a bunch of
167           debug messages to the system log. Select this if you are having a
168           problem with the driver core and want to see more of what is
169           going on.
170 
171           If you are unsure about this, say N here.
172 
173 config DEBUG_DEVRES
174         bool "Managed device resources verbose debug messages"
175         depends on DEBUG_KERNEL
176         help
177           This option enables kernel parameter devres.log. If set to
178           non-zero, devres debug messages are printed. Select this if
179           you are having a problem with devres or want to debug
180           resource management for a managed device. devres.log can be
181           switched on and off from sysfs node.
182 
183           If you are unsure about this, Say N here.
184 
185 config SYS_HYPERVISOR
186         bool
187         default n
188 
189 config GENERIC_CPU_DEVICES
190         bool
191         default n
192 
193 config GENERIC_CPU_AUTOPROBE
194         bool
195 
196 config SOC_BUS
197         bool
198 
199 source "drivers/base/regmap/Kconfig"
200 
201 config DMA_SHARED_BUFFER
202         bool
203         default n
204         select ANON_INODES
205         help
206           This option enables the framework for buffer-sharing between
207           multiple drivers. A buffer is associated with a file using driver
208           APIs extension; the file's descriptor can then be passed on to other
209           driver.
210 
211 config DMA_CMA
212         bool "DMA Contiguous Memory Allocator"
213         depends on HAVE_DMA_CONTIGUOUS && CMA
214         help
215           This enables the Contiguous Memory Allocator which allows drivers
216           to allocate big physically-contiguous blocks of memory for use with
217           hardware components that do not support I/O map nor scatter-gather.
218 
219           For more information see <include/linux/dma-contiguous.h>.
220           If unsure, say "n".
221 
222 if  DMA_CMA
223 comment "Default contiguous memory area size:"
224 
225 config CMA_SIZE_MBYTES
226         int "Size in Mega Bytes"
227         depends on !CMA_SIZE_SEL_PERCENTAGE
228         default 16
229         help
230           Defines the size (in MiB) of the default memory area for Contiguous
231           Memory Allocator.
232 
233 config CMA_SIZE_PERCENTAGE
234         int "Percentage of total memory"
235         depends on !CMA_SIZE_SEL_MBYTES
236         default 10
237         help
238           Defines the size of the default memory area for Contiguous Memory
239           Allocator as a percentage of the total memory in the system.
240 
241 choice
242         prompt "Selected region size"
243         default CMA_SIZE_SEL_MBYTES
244 
245 config CMA_SIZE_SEL_MBYTES
246         bool "Use mega bytes value only"
247 
248 config CMA_SIZE_SEL_PERCENTAGE
249         bool "Use percentage value only"
250 
251 config CMA_SIZE_SEL_MIN
252         bool "Use lower value (minimum)"
253 
254 config CMA_SIZE_SEL_MAX
255         bool "Use higher value (maximum)"
256 
257 endchoice
258 
259 config CMA_ALIGNMENT
260         int "Maximum PAGE_SIZE order of alignment for contiguous buffers"
261         range 4 12
262         default 8
263         help
264           DMA mapping framework by default aligns all buffers to the smallest
265           PAGE_SIZE order which is greater than or equal to the requested buffer
266           size. This works well for buffers up to a few hundreds kilobytes, but
267           for larger buffers it just a memory waste. With this parameter you can
268           specify the maximum PAGE_SIZE order for contiguous buffers. Larger
269           buffers will be aligned only to this specified order. The order is
270           expressed as a power of two multiplied by the PAGE_SIZE.
271 
272           For example, if your system defaults to 4KiB pages, the order value
273           of 8 means that the buffers will be aligned up to 1MiB only.
274 
275           If unsure, leave the default value "8".
276 
277 config CMA_AREAS
278         int "Maximum count of the CMA device-private areas"
279         default 7
280         help
281           CMA allows to create CMA areas for particular devices. This parameter
282           sets the maximum number of such device private CMA areas in the
283           system.
284 
285           If unsure, leave the default value "7".
286 
287 endif
288 
289 endmenu

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