build: Add RELOCADDR to i386/pc386 options

Update #3818.

spec/build/bsps/i386/pc386/grp.yml

@@ -23,6 +23,8 @@ links:
   uid: objsmpstart
 - role: build-dependency
   uid: objvga
+- role: build-dependency
+  uid: optrelocaddr
 - role: build-dependency
   uid: optvberm
 - role: build-dependency

spec/build/bsps/i386/pc386/optrelocaddr.yml

@@ -0,0 +1,27 @@
+SPDX-License-Identifier: CC-BY-SA-4.0 OR BSD-2-Clause
+actions:
+- get-integer: null
+- assert-uint32: null
+- env-assign: null
+- set-value: -Wl,-Ttext,${RELOCADDR:#010x}
+- substitute: null
+- env-append: LDFLAGS
+- env-append: PKGCONFIG_LDFLAGS
+build-type: option
+copyrights:
+- Copyright (C) 2020 embedded brains GmbH (http://www.embedded-brains.de)
+default: 1048576
+default-by-variant: []
+description: |
+  Set the value of RELOCADDR to the address where you want your image to load.
+  If you'll be using GRUB to load the images it will have to be >= 0x100000
+  (1024K). If you are using NetBoot to load the images it can be
+  >= 0x10000 (64K) AND <= 0x97C00 (607K) OR >= 0x100000 (1024K). The memory
+  top is of course another limit. Make sure there is enough space before the
+  upper memory limits for the image and the memory allocated by it to fit.
+  Make sure the value you choose is aligned to 4 bytes.
+enabled-by: true
+format: '{:#010x}'
+links: []
+name: RELOCADDR
+type: build