Build initrd tools with musl-libc (issue #77).

This adds compilations modules for musl-libc and kernel-headers.
The entire initrd (busybox, cryptsetup, gpgv, kexec, etc) can be built
with the much smaller libc and it appears to work with chroot.

Library paths are not set correctly and files are installed into
heads/install to make them accessible to other modules.  This prevents
the initrd from working without manual fixup; need to fix before
merging into master.

Build times have gone up since everything is being rebuilt more
often for some reason.

Makefile

@@ -8,6 +8,11 @@ INSTALL		:= $(pwd)/install
 # Currently supported targets are x230, chell and qemu
 BOARD		?= qemu
 
+# If musl-libc is being used in the initrd, set the heads_cc
+# variable to point to it.
+musl_dep	:= musl
+heads_cc	:= $(INSTALL)/bin/musl-gcc
+
 all: $(BOARD).rom
 
 # Disable all built in rules
@@ -68,7 +73,8 @@ define define_module =
     $(build)/$($1_dir)/.canary: $(packages)/.$1_verify
 	tar -xf "$(packages)/$($1_tar)" -C "$(build)"
 	if [ -r patches/$1-$($1_version).patch ]; then \
-		( cd $(build)/$($1_dir) ; patch -p1 ) < patches/$1-$($1_version).patch; \
+		( cd $(build)/$($1_dir) ; patch -p1 ) \
+			< patches/$1-$($1_version).patch; \
 	fi
 	touch "$$@"
   endif
@@ -100,6 +106,7 @@ define define_module =
   # Target for all of the outputs, which depend on their dependent modules
   $1.intermediate: \
 		$(foreach d,$($1_depends),$(call outputs,$d)) \
+		$(foreach d,$($1_depends),$d.intermediate) \
 		$(build)/$($1_dir)/.configured
 	make -C "$(build)/$($1_dir)" $($1_target)
 
@@ -163,16 +170,21 @@ initrd/bin/busybox: $(build)/$(busybox_dir)/busybox
 	cmp --quiet "$@" "$^" || \
 	make \
 		-C $(build)/$(busybox_dir) \
+		CC="$(heads_cc)" \
 		CONFIG_PREFIX="$(pwd)/initrd" \
+		-j 8 \
 		install
 
 # hack to build cbmem from coreboot
+# this must be built *AFTER* musl
 initrd_bins += initrd/bin/cbmem
 initrd/bin/cbmem: $(build)/$(coreboot_dir)/util/cbmem/cbmem
 	cmp --quiet "$^" "$@" \
 	|| cp "$^" "$@"
-$(build)/$(coreboot_dir)/util/cbmem/cbmem: $(build)/$(coreboot_dir)/.canary
-	make -C "$(dir $@)"
+$(build)/$(coreboot_dir)/util/cbmem/cbmem: \
+		$(build)/$(coreboot_dir)/.canary \
+		musl.intermediate
+	make -C "$(dir $@)" CC="$(heads_cc)"
 
 
 # Update all of the libraries in the initrd based on the executables

modules/busybox

@@ -6,7 +6,13 @@ busybox_tar := busybox-$(busybox_version).tar.bz2
 busybox_url := https://busybox.net/downloads/$(busybox_tar)
 busybox_hash := 5a0fe06885ee1b805fb459ab6aaa023fe4f2eccee4fb8c0fd9a6c17c0daca2fc
 
-busybox_configure := make oldconfig
+busybox_configure := make CC=$(heads_cc) oldconfig
 busybox_config := busybox.config
 busybox_output := busybox
+busybox_target := \
+	CC="$(heads_cc)" \
+	CONFIG_PREFIX="$(INSTALL)" \
+	-j 8 \
+	install
 
+busybox_depends := $(musl_dep)

modules/cryptsetup

@@ -1,6 +1,6 @@
 modules += cryptsetup
 
-cryptsetup_depends := libuuid popt lvm2
+cryptsetup_depends := libuuid popt lvm2 $(musl_dep)
 
 cryptsetup_version := 1.7.3
 cryptsetup_dir := cryptsetup-$(cryptsetup_version)
@@ -9,6 +9,7 @@ cryptsetup_url := https://www.kernel.org/pub/linux/utils/cryptsetup/v1.7/cryptse
 cryptsetup_hash := af2b04e8475cf40b8d9ffd97a1acfa73aa787c890430afd89804fb544d6adc02
 
 cryptsetup_configure := ./configure \
+	CC="$(heads_cc)" \
 	CFLAGS="-I$(INSTALL)/include" \
 	LDFLAGS="-L$(INSTALL)/lib" \
 	--prefix "$(INSTALL)" \

modules/gpg

@@ -9,6 +9,7 @@ gpg_url := https://www.gnupg.org/ftp/gcrypt/gnupg/$(gpg_tar)
 gpg_hash := 6b47a3100c857dcab3c60e6152e56a997f2c7862c1b8b2b25adf3884a1ae2276
 
 gpg_configure := ./configure \
+	CC="$(heads_cc)" \
 	CFLAGS="-I$(INSTALL)/include" \
 	LDFLAGS="-L$(INSTALL)/lib" \
 	--prefix $(INSTALL) \
@@ -35,3 +36,4 @@ gpg_target := -j 8 install
 
 gpg_output := g10/gpgv
 
+gpg_depends := $(musl_dep)

modules/kernel-headers

@@ -0,0 +1,18 @@
+modules += kernel-headers
+
+# we install kernel-headers from sabotage linux, a musl-libc based
+# distribution, that works well with busybox and other tools.
+
+kernel-headers_version := 3.12.6-5
+kernel-headers_dir := kernel-headers-$(kernel-headers_version)
+kernel-headers_tar := kernel-headers-$(kernel-headers_version).tar.gz
+kernel-headers_url := https://github.com/sabotage-linux/kernel-headers/archive/v$(kernel-headers_version).tar.gz
+kernel-headers_hash := ecf4db8781dc50a21cbc4cb17b039f96aede53f9da13435a3201373abb49b96b
+
+kernel-headers_configure :=
+
+kernel-headers_target := \
+	ARCH=x86_64 \
+	prefix="$(INSTALL)" \
+	install
+

modules/kexec

@@ -7,15 +7,20 @@ kexec_url := https://kernel.org/pub/linux/utils/kernel/kexec/$(kexec_tar)
 kexec_hash := cc7b60dad0da202004048a6179d8a53606943062dd627a2edba45a8ea3a85135
 
 kexec_configure := ./configure \
+	CC="$(heads_cc)" \
 	CFLAGS="-I$(INSTALL)/include" \
 	LDFLAGS="-L$(INSTALL)/lib" \
 	--prefix="$(INSTALL)" \
 	--without-zlib \
 	--without-lzma \
 
-kexec_target := -j 8 install
+kexec_target := \
+	CC="$(heads_cc)" \
+	-j 8 \
+	install \
 
 kexec_output := build/sbin/kexec
 
 # if we don't need zlib, don't built it
 #kexec_depends := zlib
+kexec_depends := $(musl_dep)

modules/libuuid

@@ -7,8 +7,10 @@ libuuid_url := http://downloads.sourceforge.net/project/libuuid/$(libuuid_tar)
 libuuid_hash := 46af3275291091009ad7f1b899de3d0cea0252737550e7919d17237997db5644
 
 libuuid_configure := ./configure \
+	CC="$(heads_cc)" \
 	--prefix $(INSTALL) \
 
 libuuid_target := install
 
 libuuid_libraries := .libs/libuuid.so
+libuuid_depends := $(musl_dep)

modules/lvm2

@@ -7,6 +7,7 @@ lvm2_url := http://mirrors.kernel.org/sourceware/lvm2/$(lvm2_tar)
 lvm2_hash := 23a3d1cddd41b3ef51812ebf83e9fa491f502fe74130d4263be327a91914660d
 
 lvm2_configure := ./configure \
+	CC="$(heads_cc)" \
 	--prefix $(INSTALL) \
 	--disable-selinux \
 	--disable-udev-systemd-background-jobs \
@@ -17,3 +18,5 @@ lvm2_target := -j 8 install_device-mapper
 lvm2_libraries := libdm/libdevmapper.so
 
 lvm2_output := tools/dmsetup
+
+lvm2_depends := $(musl_dep)

modules/mbedtls

@@ -10,4 +10,11 @@ mbedtls_libraries := \
 	library/libmbedcrypto.so.0 \
 
 mbedtls_configure :=
-mbedtls_target := SHARED=1 DESTDIR=$(INSTALL) -j 8 install
+mbedtls_target := \
+	SHARED=1 \
+	DESTDIR=$(INSTALL) \
+	CC="$(heads_cc)" \
+	-j 8 \
+	install
+
+mbedtls_depends := $(musl_dep)

modules/musl

@@ -0,0 +1,17 @@
+modules += musl
+
+musl_version := 1.1.15
+musl_dir := musl-$(musl_version)
+musl_tar := musl-$(musl_version).tar.gz
+musl_url := https://www.musl-libc.org/releases/$(musl_tar)
+musl_hash := 97e447c7ee2a7f613186ec54a93054fe15469fe34d7d323080f7ef38f5ecb0fa
+
+musl_output := $(INSTALL)/bin/musl-gcc
+
+musl_configure := ./configure \
+	--prefix="$(INSTALL)" \
+	--syslibdir="$(INSTALL)/lib" \
+
+musl_target := -j 8 install
+
+musl_depends := kernel-headers

modules/popt

@@ -7,8 +7,10 @@ popt_url := http://rpm5.org/files/popt/$(popt_tar)
 popt_hash := e728ed296fe9f069a0e005003c3d6b2dde3d9cad453422a10d6558616d304cc8
 
 popt_configure := ./configure \
+	CC="$(heads_cc)" \
 	--prefix $(INSTALL) \
 
 popt_target := install
 
 popt_libraries := ./libs/libpopt.so
+popt_depends := $(musl_dep)

modules/qrencode

@@ -9,8 +9,10 @@ qrencode_hash := e794e26a96019013c0e3665cb06b18992668f352c5553d0a553f5d144f7f2a7
 qrencode_output := .libs/libqrencode.so.$(qrencode_version)
 
 qrencode_configure := ./configure \
+	CC="$(heads_cc)" \
 	--prefix $(INSTALL) \
 	--without-tools \
 
 qrencode_target := install
 
+qrencode_depends := $(musl_dep)

modules/tpmtotp

@@ -1,6 +1,6 @@
 modules += tpmtotp
 
-tpmtotp_depends := mbedtls qrencode
+tpmtotp_depends := mbedtls qrencode $(musl_dep)
 
 tpmtotp_version := git
 tpmtotp_repo := https://github.com/osresearch/tpmtotp
@@ -11,6 +11,7 @@ tpmtotp_dir := tpmtotp-$(tpmtotp_version)
 #tpmtotp_url := https://github.com/osresearch/tpmtotp/archive/v0.0.1.tar.gz
 #tpmtotp_hash := 8bf2380248fea540a96ad0ff8a4f170b8d93b6bb5fe49b958f9f1926f994823f
 
+tpmtotp_target := CC="$(heads_cc)"
 
 tpmtotp_output := \
 	totp \