From 1459e701e3c867dcede633e6ed4000491a4dfc67 Mon Sep 17 00:00:00 2001
From: Trammell hudson <hudson@trmm.net>
Date: Tue, 13 Feb 2018 17:46:48 -0500
Subject: [PATCH] Make the Heads runtime opt-out from the initrd.cpio.  #317

Allow sub-modules like u-root to opt out of the Heads runtime,
while retaining the musl-libc built tools.
---
 Makefile                 |  7 +++++--
 boards/winterfell.config | 18 ++++++++++++------
 modules/u-root           | 10 +++++-----
 3 files changed, 22 insertions(+), 13 deletions(-)

diff --git a/Makefile b/Makefile
index e39c428f..a371f182 100644
--- a/Makefile
+++ b/Makefile
@@ -18,6 +18,9 @@ endif
 
 include $(CONFIG)
 
+# Unless otherwise specified, we are building for heads
+CONFIG_HEADS	?= y
+
 # Controls how many parallel jobs are invoked in subshells
 CPUS		:= $(shell nproc)
 MAKE_JOBS	?= -j$(CPUS) --max-load 16
@@ -386,12 +389,12 @@ $(build)/$(coreboot_dir)/util/cbmem/cbmem: \
 #
 
 initrd-y += $(pwd)/blobs/dev.cpio
-initrd-y += $(build)/$(BOARD)/heads.cpio
 initrd-y += $(build)/$(BOARD)/modules.cpio
 initrd-y += $(build)/$(BOARD)/tools.cpio
+initrd-$(CONFIG_HEADS) += $(build)/$(BOARD)/heads.cpio
 
 initrd.intermediate: $(build)/$(BOARD)/initrd.cpio.xz
-$(build)/$(BOARD)/initrd.cpio.xz: $(or $(INITRD_OVERRIDE),$(initrd-y))
+$(build)/$(BOARD)/initrd.cpio.xz: $(initrd-y)
 	$(call do,CPIO-CLEAN,$@,\
 	$(pwd)/bin/cpio-clean \
 		$^ \
diff --git a/boards/winterfell.config b/boards/winterfell.config
index aa862f64..d946bdfc 100644
--- a/boards/winterfell.config
+++ b/boards/winterfell.config
@@ -4,24 +4,30 @@ CONFIG_LINUXBOOT=y
 CONFIG_LINUXBOOT_ROM=blobs/winterfell.rom
 CONFIG_LINUX_CONFIG=config/linux-linuxboot.config
 
-# If you want to build with the go-based u-root instead of
-# everything else.  Note that turning this on will turn off
-# all of the other build tools.
+# If you want to build with the go-based u-root instead of Heads
 CONFIG_UROOT=y
 
+ifeq "$(CONFIG_UROOT)" "y"
+# The busybox will likely be redundant and can be trimmed for space.
+CONFIG_BUSYBOX=n
+CONFIG_ZLIB=n
+CONFIG_MUSL=n
+else
+# These don't fit if u-root is turned on
 CONFIG_CRYPTSETUP=y
 CONFIG_FLASHROM=y
-#CONFIG_GPG=y
+CONFIG_GPG=y
 CONFIG_KEXEC=y
 CONFIG_UTIL_LINUX=y
 CONFIG_LVM2=y
-#CONFIG_MBEDTLS=y
+CONFIG_MBEDTLS=y
 CONFIG_PCIUTILS=y
 CONFIG_POPT=y
 #CONFIG_QRENCODE=y
 #CONFIG_TPMTOTP=y
-#CONFIG_XEN=y
+CONFIG_XEN=y
 CONFIG_DROPBEAR=y
+endif
 
 # Linux modules will still be linked into the u-root tree
 CONFIG_LINUX_USB=y
diff --git a/modules/u-root b/modules/u-root
index ecdf2abc..0720a640 100644
--- a/modules/u-root
+++ b/modules/u-root
@@ -5,10 +5,8 @@
 # own dependencies.
 #
 
-ifeq "$(CONFIG_UROOT)" "y"
-
 u-root_url := github.com/u-root/u-root
-u-root_output := $(build)/$(BOARD)/initrd.cpio
+u-root_output := $(build)/$(BOARD)/u-root.cpio
 
 export GOPATH=$(build)/go
 
@@ -26,8 +24,10 @@ $(u-root_output): $(GOPATH)
 	)
 
 # Override the initrd inputs and add in the kernel modules
-INITRD_OVERRIDE += $(u-root_output)
-INITRD_OVERRIDE += $(build)/$(BOARD)/modules.cpio
+initrd-$(CONFIG_UROOT) += $(u-root_output)
 
 
+# If we are building for u-root, disable the default CONFIG_HEADS
+ifeq "$(CONFIG_UROOT)" "y"
+CONFIG_HEADS=n
 endif