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 The kernel source tree includes a number of firmware 'blobs' that are used by various drivers. The recommended way to use these is to run "make firmware_install", which, after converting ihex files to binary, copies all of the needed binary files in firmware/ to /lib/firmware/ on your system so that they can be loaded by userspace helpers on request. Enabling this option will build each required firmware blob 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 do not wish to use an initrd. This single option controls the inclusion of firmware for every driver that uses request_firmware() and ships its firmware in the kernel source tree, 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 "firmware" help This option controls the directory in which the kernel build system looks for the firmware files listed in the EXTRA_FIRMWARE option. The default is firmware/ in the kernel source tree, but by changing this option you can point it elsewhere, such as /lib/firmware/ or some other directory containing the firmware files. 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. 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 source "drivers/base/regmap/Kconfig" config DMA_SHARED_BUFFER bool default n select ANON_INODES 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 DMABUF_DEFERRED_UNMAPPING bool "Defer unmapping till shared DMA buffer is free" default y depends on DMA_SHARED_BUFFER help This option enables the buffer-sharing framework to use deferred unmapping. Buffer mapping would be reused and kept repeatedly until dmabuf is freed. Dmabuf exporter can specify if it is compatible with this option. config FENCE_TRACE bool "Enable verbose FENCE_TRACE messages" depends on DMA_SHARED_BUFFER help Enable the 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 . 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 endmenu