$NetBSD: README.compileopts,v 1.4 2014/04/23 23:25:45 pooka Exp $

This file describes compile-time options for rump kernels.  Additionally,
NetBSD build options will have an effect.  See src/share/mk/bsd.README
for a desciption of NetBSD build options.

Note: after changing an option, do a clean build.


    RUMP_DIAGNOSTIC

values:	yes|no
defval:	yes
effect:	Iff "yes", build with -DDIAGNOSTIC.


    RUMP_DEBUG

values:	defined / not defined
effect:	Iff defined, build with -DDEBUG.


    RUMP_LOCKDEBUG

values:	defined / not defined
effect:	Iff defined, build with -DLOCKDEBUG.


    RUMP_KTRACE

values:	yes|no
defval:	yes
effect:	Iff "yes", build with -DKTRACE.


    RUMP_LOCKS_UP

values: yes|no
defval:	no
effect: If "yes", build rump kernel with uniprocess-optimized locking.
	An implication of this is that RUMP_NCPU==1 is required at
	runtime.  If "no", build with multiprocessor-capable locking.


    RUMP_UNREAL_ALLOCATORS

values: yes|no
defval:	no
effect: If "yes", build version of kmem_alloc, pool and pool_cache
	that directly relegate allocation to a hypercall.  If "no",
	build the regular NetBSD memory allocators which use
	page-sized memory allocation hypercalls.


    RUMP_VIRTIF

values:	yes|no
defval:	yes
effect:	Iff "yes", build the virt(4) network interface.  Turning this
	off may be necessary on systems that lack the necessary headers,
	e.g. musl libc based Linux.


    RUMP_CURLWP

values: hypercall/__thread/register or <undefined>
defval: <undefined>
effect: Control how curlwp is obtained in a rump kernel.  This is
	a very frequently accessed thread-local variable, and optimizing
	access has a significant performance impact.  Note that all
	options are not available on hosts/machine architectures.
	<undefined> - use default implementation (currently "hypercall")
	hypercall   - use a hypercall to fetch the value
	__thread    - use the __thread feature to fetch value via TLS
	register    - use a dedicated register (implies -ffixed)


================================================================================


The rest of the options described in this file are not intended to be
set by users, but by the package building rump kernels.


    RUMP_KERNEL_IS_LIBC

values:	defined / not defined
effect: Iff defined, export normal system call symbols from libc.
	For example, without this option rump_sys_open() is exported.
	With this option, both open() and rump_sys_open() are exported.
	This option is meant for building systems where a rump kernel
	is the only operating system like component.


    RUMP_LDSCRIPT

values: no/GNU/sun/ctor
defval: GNU
effect: Select the linker script to be used for linking rump kernel shared
	library components.
	no	- do not use a linker script
	GNU	- use a linker script for GNU ld 2.18 and later
	sun	- use a linker script for the Solaris linker
	ctor	- do not use a linker script, make the code
		  generate __attribute__((constructor))