Path to uevent helper program 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.
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.
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 roots 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.
Select this option if you don't have magic firmware for drivers that need it. If unsure, say Y.
Say yes to avoid building firmware. Firmware is usually shipped with the driver, and only when updating the firmware a rebuild should be made. If unsure say Y here.
This option is provided for the case where no in-kernel-tree modules require userspace firmware loading support, but a module built outside the kernel tree does.
The kernel source tree includes a number of firmware 'blobs' which are used by various drivers. The recommended way to use these is to run "make firmware_install" and to copy the resulting binary files created in usr/lib/firmware directory of the kernel tree to the /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 which uses such firmware, and do not wish to use an initrd. This single option controls the inclusion of firmware for every driver which uses request_firmware() and ships its firmware in the kernel source tree, to avoid a proliferation of 'Include firmware for xxx device' options. Say 'N' and let firmware be loaded from userspace.
This option allows firmware to be built into the kernel, for the cases 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 which 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. So, 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 which 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.
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 the firmware/ directory in the kernel source tree, but by changing this option you can point it elsewhere, such as the /lib/firmware/ directory or another separate directory containing firmware files.
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.
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.