# make buildworld
[...]
===> usr.bin/kdump
sh /usr/src/usr.bin/kdump/mkioctls
/usr/obj/usr/src/world_i386/usr/include > ioctl.c
/usr/src/usr.bin/kdump/mkioctls: awk: Argument list too long
/usr/src/usr.bin/kdump/mkioctls: awk: Argument list too long
This is a valid error, but you should be able to work around it by
running make cleandir in all module directories where you manually built
modules. At least this used to be the cause.