svn commit: r276846 - in head: share/mk sys/arm/conf sys/conf sys/modules/dtb sys/modules/dtb/atmel

[NGie Cooper]

On Thu, Jan 8, 2015 at 10:28 AM, Warner Losh <imp at freebsd.org> wrote:
> Author: imp
> Date: Thu Jan  8 18:28:06 2015
> New Revision: 276846
> URL: https://svnweb.freebsd.org/changeset/base/276846
>
> Log:
>   Add infrastructure to build dtb files from dts files.

...

> Added: head/share/mk/bsd.dtb.mk
> ==============================================================================
> --- /dev/null   00:00:00 1970   (empty, because file is newly added)
> +++ head/share/mk/bsd.dtb.mk    Thu Jan  8 18:28:06 2015        (r276846)
> @@ -0,0 +1,17 @@
> +# $FreeBSD$
> +
> +# Search for kernel source tree in standard places.
> +.for _dir in ${.CURDIR}/../.. ${.CURDIR}/../../.. ${.CURDIR}/../../../.. \
> +    ${.CURDIR}/../../../../.. /sys /usr/src/sys
> +.if !defined(SYSDIR) && exists(${_dir}/kern/) && exists(${_dir}/conf/kmod.mk)
> +SYSDIR=        ${_dir}
> +.endif
> +.endfor
> +.if !defined(SYSDIR) || !exists(${SYSDIR}/kern/) || \
> +    !exists(${SYSDIR}/conf/kmod.mk)
> +.error Unable to locate the kernel source tree. Set SYSDIR to override.
> +.endif
> +
> +.include "${SYSDIR}/conf/dtb.mk"
> +
> +.include <bsd.sys.mk>

...

> +# Search for kernel source tree in standard places.
> +.for _dir in ${.CURDIR}/../.. ${.CURDIR}/../../.. /sys /usr/src/sys
> +.if !defined(SYSDIR) && exists(${_dir}/kern/)
> +SYSDIR=        ${_dir}
> +.endif
> +.endfor
> +.if !defined(SYSDIR) || !exists(${SYSDIR}/kern/)
> +.error "can't find kernel source tree"
> +.endif

Why is ${SYSDIR} being checked for in bsd.dtb.mk and dtb.mk?