xref: /linux/drivers/base/Kconfig (revision 52cf25d0ab7f78eeecc59ac652ed5090f69b619e)
1menu "Generic Driver Options"
2
3config UEVENT_HELPER_PATH
4	string "path to uevent helper"
5	depends on HOTPLUG
6	default ""
7	help
8	  Path to uevent helper program 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 DEVTMPFS
20	bool "Maintain a devtmpfs filesystem to mount at /dev"
21	depends on HOTPLUG && SHMEM && TMPFS
22	help
23	  This creates a tmpfs filesystem instance early at bootup.
24	  In this filesystem, the kernel driver core maintains device
25	  nodes with their default names and permissions for all
26	  registered devices with an assigned major/minor number.
27	  Userspace can modify the filesystem content as needed, add
28	  symlinks, and apply needed permissions.
29	  It provides a fully functional /dev directory, where usually
30	  udev runs on top, managing permissions and adding meaningful
31	  symlinks.
32	  In very limited environments, it may provide a sufficient
33	  functional /dev without any further help. It also allows simple
34	  rescue systems, and reliably handles dynamic major/minor numbers.
35
36config DEVTMPFS_MOUNT
37	bool "Automount devtmpfs at /dev, after the kernel mounted the rootfs"
38	depends on DEVTMPFS
39	help
40	  This will instruct the kernel to automatically mount the
41	  devtmpfs filesystem at /dev, directly after the kernel has
42	  mounted the root filesystem. The behavior can be overridden
43	  with the commandline parameter: devtmpfs.mount=0|1.
44	  This option does not affect initramfs based booting, here
45	  the devtmpfs filesystem always needs to be mounted manually
46	  after the roots is mounted.
47	  With this option enabled, it allows to bring up a system in
48	  rescue mode with init=/bin/sh, even when the /dev directory
49	  on the rootfs is completely empty.
50
51config STANDALONE
52	bool "Select only drivers that don't need compile-time external firmware" if EXPERIMENTAL
53	default y
54	help
55	  Select this option if you don't have magic firmware for drivers that
56	  need it.
57
58	  If unsure, say Y.
59
60config PREVENT_FIRMWARE_BUILD
61	bool "Prevent firmware from being built"
62	default y
63	help
64	  Say yes to avoid building firmware. Firmware is usually shipped
65	  with the driver, and only when updating the firmware a rebuild
66	  should be made.
67	  If unsure say Y here.
68
69config FW_LOADER
70	tristate "Userspace firmware loading support" if EMBEDDED
71	depends on HOTPLUG
72	default y
73	---help---
74	  This option is provided for the case where no in-kernel-tree modules
75	  require userspace firmware loading support, but a module built outside
76	  the kernel tree does.
77
78config FIRMWARE_IN_KERNEL
79	bool "Include in-kernel firmware blobs in kernel binary"
80	depends on FW_LOADER
81	default y
82	help
83	  The kernel source tree includes a number of firmware 'blobs'
84	  which are used by various drivers. The recommended way to
85	  use these is to run "make firmware_install" and to copy the
86	  resulting binary files created in usr/lib/firmware directory
87	  of the kernel tree to the /lib/firmware on your system so
88	  that they can be loaded by userspace helpers on request.
89
90	  Enabling this option will build each required firmware blob
91	  into the kernel directly, where request_firmware() will find
92	  them without having to call out to userspace. This may be
93	  useful if your root file system requires a device which uses
94	  such firmware, and do not wish to use an initrd.
95
96	  This single option controls the inclusion of firmware for
97	  every driver which uses request_firmware() and ships its
98	  firmware in the kernel source tree, to avoid a proliferation
99	  of 'Include firmware for xxx device' options.
100
101	  Say 'N' and let firmware be loaded from userspace.
102
103config EXTRA_FIRMWARE
104	string "External firmware blobs to build into the kernel binary"
105	depends on FW_LOADER
106	help
107	  This option allows firmware to be built into the kernel, for the
108	  cases where the user either cannot or doesn't want to provide it from
109	  userspace at runtime (for example, when the firmware in question is
110	  required for accessing the boot device, and the user doesn't want to
111	  use an initrd).
112
113	  This option is a string, and takes the (space-separated) names of the
114	  firmware files -- the same names which appear in MODULE_FIRMWARE()
115	  and request_firmware() in the source. These files should exist under
116	  the directory specified by the EXTRA_FIRMWARE_DIR option, which is
117	  by default the firmware/ subdirectory of the kernel source tree.
118
119	  So, for example, you might set CONFIG_EXTRA_FIRMWARE="usb8388.bin",
120	  copy the usb8388.bin file into the firmware/ directory, and build the
121	  kernel. Then any request_firmware("usb8388.bin") will be
122	  satisfied internally without needing to call out to userspace.
123
124	  WARNING: If you include additional firmware files into your binary
125	  kernel image which are not available under the terms of the GPL,
126	  then it may be a violation of the GPL to distribute the resulting
127	  image -- since it combines both GPL and non-GPL work. You should
128	  consult a lawyer of your own before distributing such an image.
129
130config EXTRA_FIRMWARE_DIR
131	string "Firmware blobs root directory"
132	depends on EXTRA_FIRMWARE != ""
133	default "firmware"
134	help
135	  This option controls the directory in which the kernel build system
136	  looks for the firmware files listed in the EXTRA_FIRMWARE option.
137	  The default is the firmware/ directory in the kernel source tree,
138	  but by changing this option you can point it elsewhere, such as
139	  the /lib/firmware/ directory or another separate directory
140	  containing firmware files.
141
142config DEBUG_DRIVER
143	bool "Driver Core verbose debug messages"
144	depends on DEBUG_KERNEL
145	help
146	  Say Y here if you want the Driver core to produce a bunch of
147	  debug messages to the system log. Select this if you are having a
148	  problem with the driver core and want to see more of what is
149	  going on.
150
151	  If you are unsure about this, say N here.
152
153config DEBUG_DEVRES
154	bool "Managed device resources verbose debug messages"
155	depends on DEBUG_KERNEL
156	help
157	  This option enables kernel parameter devres.log. If set to
158	  non-zero, devres debug messages are printed. Select this if
159	  you are having a problem with devres or want to debug
160	  resource management for a managed device. devres.log can be
161	  switched on and off from sysfs node.
162
163	  If you are unsure about this, Say N here.
164
165config SYS_HYPERVISOR
166	bool
167	default n
168
169endmenu
170