| # SPDX-License-Identifier: GPL-2.0 |
| menu "Generic Driver Options" |
| |
| config UEVENT_HELPER |
| bool "Support for uevent helper" |
| default y |
| help |
| The uevent helper program is forked by the kernel for |
| every uevent. |
| Before the switch to the netlink-based uevent source, this was |
| used to hook hotplug scripts into kernel device events. It |
| usually pointed to a shell script at /sbin/hotplug. |
| This should not be used today, because usual systems create |
| many events at bootup or device discovery in a very short time |
| frame. One forked process per event can create so many processes |
| that it creates a high system load, or on smaller systems |
| it is known to create out-of-memory situations during bootup. |
| |
| config UEVENT_HELPER_PATH |
| string "path to uevent helper" |
| depends on UEVENT_HELPER |
| default "" |
| help |
| To disable user space helper program execution at by default |
| specify an empty string here. This setting can still be altered |
| via /proc/sys/kernel/hotplug or via /sys/kernel/uevent_helper |
| later at runtime. |
| |
| config DEVTMPFS |
| bool "Maintain a devtmpfs filesystem to mount at /dev" |
| help |
| This creates a tmpfs/ramfs filesystem instance early at bootup. |
| In this filesystem, the kernel driver core maintains device |
| nodes with their default names and permissions for all |
| registered devices with an assigned major/minor number. |
| Userspace can modify the filesystem content as needed, add |
| symlinks, and apply needed permissions. |
| It provides a fully functional /dev directory, where usually |
| udev runs on top, managing permissions and adding meaningful |
| symlinks. |
| In very limited environments, it may provide a sufficient |
| functional /dev without any further help. It also allows simple |
| rescue systems, and reliably handles dynamic major/minor numbers. |
| |
| Notice: if CONFIG_TMPFS isn't enabled, the simpler ramfs |
| file system will be used instead. |
| |
| config DEVTMPFS_MOUNT |
| bool "Automount devtmpfs at /dev, after the kernel mounted the rootfs" |
| depends on DEVTMPFS |
| help |
| This will instruct the kernel to automatically mount the |
| devtmpfs filesystem at /dev, directly after the kernel has |
| mounted the root filesystem. The behavior can be overridden |
| with the commandline parameter: devtmpfs.mount=0|1. |
| This option does not affect initramfs based booting, here |
| the devtmpfs filesystem always needs to be mounted manually |
| after the rootfs is mounted. |
| With this option enabled, it allows to bring up a system in |
| rescue mode with init=/bin/sh, even when the /dev directory |
| on the rootfs is completely empty. |
| |
| config STANDALONE |
| bool "Select only drivers that don't need compile-time external firmware" |
| default y |
| help |
| Select this option if you don't have magic firmware for drivers that |
| need it. |
| |
| If unsure, say Y. |
| |
| config PREVENT_FIRMWARE_BUILD |
| bool "Prevent firmware from being built" |
| default y |
| help |
| Say yes to avoid building firmware. Firmware is usually shipped |
| with the driver and only when updating the firmware should a |
| rebuild be made. |
| If unsure, say Y here. |
| |
| config FW_LOADER |
| tristate "Userspace firmware loading support" if EXPERT |
| default y |
| ---help--- |
| This option is provided for the case where none of the in-tree modules |
| require userspace firmware loading support, but a module built |
| out-of-tree does. |
| |
| config FIRMWARE_IN_KERNEL |
| bool "Include in-kernel firmware blobs in kernel binary" |
| depends on FW_LOADER |
| default y |
| help |
| Various drivers in the kernel source tree may require firmware, |
| which is generally available in your distribution's linux-firmware |
| package. |
| |
| The linux-firmware package should install firmware into |
| /lib/firmware/ on your system, so they can be loaded by userspace |
| helpers on request. |
| |
| Enabling this option will build each required firmware blob |
| specified by EXTRA_FIRMWARE into the kernel directly, where |
| request_firmware() will find them without having to call out to |
| userspace. This may be useful if your root file system requires a |
| device that uses such firmware and you do not wish to use an |
| initrd. |
| |
| This single option controls the inclusion of firmware for |
| every driver that uses request_firmware(), which avoids a |
| proliferation of 'Include firmware for xxx device' options. |
| |
| Say 'N' and let firmware be loaded from userspace. |
| |
| config EXTRA_FIRMWARE |
| string "External firmware blobs to build into the kernel binary" |
| depends on FW_LOADER |
| help |
| This option allows firmware to be built into the kernel for the case |
| where the user either cannot or doesn't want to provide it from |
| userspace at runtime (for example, when the firmware in question is |
| required for accessing the boot device, and the user doesn't want to |
| use an initrd). |
| |
| This option is a string and takes the (space-separated) names of the |
| firmware files -- the same names that appear in MODULE_FIRMWARE() |
| and request_firmware() in the source. These files should exist under |
| the directory specified by the EXTRA_FIRMWARE_DIR option, which is |
| by default the firmware subdirectory of the kernel source tree. |
| |
| For example, you might set CONFIG_EXTRA_FIRMWARE="usb8388.bin", copy |
| the usb8388.bin file into the firmware directory, and build the kernel. |
| Then any request_firmware("usb8388.bin") will be satisfied internally |
| without needing to call out to userspace. |
| |
| WARNING: If you include additional firmware files into your binary |
| kernel image that are not available under the terms of the GPL, |
| then it may be a violation of the GPL to distribute the resulting |
| image since it combines both GPL and non-GPL work. You should |
| consult a lawyer of your own before distributing such an image. |
| |
| config EXTRA_FIRMWARE_DIR |
| string "Firmware blobs root directory" |
| depends on EXTRA_FIRMWARE != "" |
| default "/lib/firmware" |
| help |
| This option controls the directory in which the kernel build system |
| looks for the firmware files listed in the EXTRA_FIRMWARE option. |
| |
| config FW_LOADER_USER_HELPER |
| bool |
| |
| config FW_LOADER_USER_HELPER_FALLBACK |
| bool "Fallback user-helper invocation for firmware loading" |
| depends on FW_LOADER |
| select FW_LOADER_USER_HELPER |
| help |
| This option enables / disables the invocation of user-helper |
| (e.g. udev) for loading firmware files as a fallback after the |
| direct file loading in kernel fails. The user-mode helper is |
| no longer required unless you have a special firmware file that |
| resides in a non-standard path. Moreover, the udev support has |
| been deprecated upstream. |
| |
| If you are unsure about this, say N here. |
| |
| config WANT_DEV_COREDUMP |
| bool |
| help |
| Drivers should "select" this option if they desire to use the |
| device coredump mechanism. |
| |
| config ALLOW_DEV_COREDUMP |
| bool "Allow device coredump" if EXPERT |
| default y |
| help |
| This option controls if the device coredump mechanism is available or |
| not; if disabled, the mechanism will be omitted even if drivers that |
| can use it are enabled. |
| Say 'N' for more sensitive systems or systems that don't want |
| to ever access the information to not have the code, nor keep any |
| data. |
| |
| If unsure, say Y. |
| |
| config DEV_COREDUMP |
| bool |
| default y if WANT_DEV_COREDUMP |
| depends on ALLOW_DEV_COREDUMP |
| |
| config DEBUG_DRIVER |
| bool "Driver Core verbose debug messages" |
| depends on DEBUG_KERNEL |
| help |
| Say Y here if you want the Driver core to produce a bunch of |
| debug messages to the system log. Select this if you are having a |
| problem with the driver core and want to see more of what is |
| going on. |
| |
| If you are unsure about this, say N here. |
| |
| config DEBUG_DEVRES |
| bool "Managed device resources verbose debug messages" |
| depends on DEBUG_KERNEL |
| help |
| This option enables kernel parameter devres.log. If set to |
| non-zero, devres debug messages are printed. Select this if |
| you are having a problem with devres or want to debug |
| resource management for a managed device. devres.log can be |
| switched on and off from sysfs node. |
| |
| If you are unsure about this, Say N here. |
| |
| config DEBUG_TEST_DRIVER_REMOVE |
| bool "Test driver remove calls during probe (UNSTABLE)" |
| depends on DEBUG_KERNEL |
| help |
| Say Y here if you want the Driver core to test driver remove functions |
| by calling probe, remove, probe. This tests the remove path without |
| having to unbind the driver or unload the driver module. |
| |
| This option is expected to find errors and may render your system |
| unusable. You should say N here unless you are explicitly looking to |
| test this functionality. |
| |
| source "drivers/base/test/Kconfig" |
| |
| config SYS_HYPERVISOR |
| bool |
| default n |
| |
| config GENERIC_CPU_DEVICES |
| bool |
| default n |
| |
| config GENERIC_CPU_AUTOPROBE |
| bool |
| |
| config GENERIC_CPU_VULNERABILITIES |
| bool |
| |
| config SOC_BUS |
| bool |
| select GLOB |
| |
| source "drivers/base/regmap/Kconfig" |
| |
| config DMA_SHARED_BUFFER |
| bool |
| default n |
| select IRQ_WORK |
| help |
| This option enables the framework for buffer-sharing between |
| multiple drivers. A buffer is associated with a file using driver |
| APIs extension; the file's descriptor can then be passed on to other |
| driver. |
| |
| config DMA_FENCE_TRACE |
| bool "Enable verbose DMA_FENCE_TRACE messages" |
| depends on DMA_SHARED_BUFFER |
| help |
| Enable the DMA_FENCE_TRACE printks. This will add extra |
| spam to the console log, but will make it easier to diagnose |
| lockup related problems for dma-buffers shared across multiple |
| devices. |
| |
| config DMA_CMA |
| bool "DMA Contiguous Memory Allocator" |
| depends on HAVE_DMA_CONTIGUOUS && CMA |
| help |
| This enables the Contiguous Memory Allocator which allows drivers |
| to allocate big physically-contiguous blocks of memory for use with |
| hardware components that do not support I/O map nor scatter-gather. |
| |
| You can disable CMA by specifying "cma=0" on the kernel's command |
| line. |
| |
| For more information see <include/linux/dma-contiguous.h>. |
| If unsure, say "n". |
| |
| if DMA_CMA |
| comment "Default contiguous memory area size:" |
| |
| config CMA_SIZE_MBYTES |
| int "Size in Mega Bytes" |
| depends on !CMA_SIZE_SEL_PERCENTAGE |
| default 0 if X86 |
| default 16 |
| help |
| Defines the size (in MiB) of the default memory area for Contiguous |
| Memory Allocator. If the size of 0 is selected, CMA is disabled by |
| default, but it can be enabled by passing cma=size[MG] to the kernel. |
| |
| |
| config CMA_SIZE_PERCENTAGE |
| int "Percentage of total memory" |
| depends on !CMA_SIZE_SEL_MBYTES |
| default 0 if X86 |
| default 10 |
| help |
| Defines the size of the default memory area for Contiguous Memory |
| Allocator as a percentage of the total memory in the system. |
| If 0 percent is selected, CMA is disabled by default, but it can be |
| enabled by passing cma=size[MG] to the kernel. |
| |
| choice |
| prompt "Selected region size" |
| default CMA_SIZE_SEL_MBYTES |
| |
| config CMA_SIZE_SEL_MBYTES |
| bool "Use mega bytes value only" |
| |
| config CMA_SIZE_SEL_PERCENTAGE |
| bool "Use percentage value only" |
| |
| config CMA_SIZE_SEL_MIN |
| bool "Use lower value (minimum)" |
| |
| config CMA_SIZE_SEL_MAX |
| bool "Use higher value (maximum)" |
| |
| endchoice |
| |
| config CMA_ALIGNMENT |
| int "Maximum PAGE_SIZE order of alignment for contiguous buffers" |
| range 4 12 |
| default 8 |
| help |
| DMA mapping framework by default aligns all buffers to the smallest |
| PAGE_SIZE order which is greater than or equal to the requested buffer |
| size. This works well for buffers up to a few hundreds kilobytes, but |
| for larger buffers it just a memory waste. With this parameter you can |
| specify the maximum PAGE_SIZE order for contiguous buffers. Larger |
| buffers will be aligned only to this specified order. The order is |
| expressed as a power of two multiplied by the PAGE_SIZE. |
| |
| For example, if your system defaults to 4KiB pages, the order value |
| of 8 means that the buffers will be aligned up to 1MiB only. |
| |
| If unsure, leave the default value "8". |
| |
| endif |
| |
| config GENERIC_ARCH_TOPOLOGY |
| bool |
| help |
| Enable support for architectures common topology code: e.g., parsing |
| CPU capacity information from DT, usage of such information for |
| appropriate scaling, sysfs interface for changing capacity values at |
| runtime. |
| |
| endmenu |