Before building a custom kernel, consider the reason for doing so. If there is a need for specific hardware support, it may already exist as a module.
Kernel modules exist in /boot/kernel
and may be
dynamically loaded into the running kernel using
kldload(8). Most, if not all kernel drivers have a
loadable module and manual page. For example, the ath(4)
wireless Ethernet driver has the following information in its
manual page:
Adding if_ath_load="YES"
to
/boot/loader.conf
will enable loading this
module dynamically at boot time.
In some cases, there is no associated module. This is mostly true for certain subsystems. One way to tell if a driver is available is to check for the module itself.
It is easy to remove support for a device or option and end up with a broken kernel. For example, if the ata(4) driver is removed from the kernel configuration file, a system using ATA disk drivers may not boot. When in doubt, just leave support in the kernel.
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sent to <freebsd-questions@FreeBSD.org>.
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