Shuffle around the creation of sysb

For further RAM savings, we want to create sysb -without- having linux
tarball extracted at the same time. To accomplish this, we move the
gen_init_cpio + related script out of the tree and create it afterward.

Also use hard links to free up some more space.

sysa/linux-4.9.10/files/config

@@ -177,7 +177,7 @@ CONFIG_SCHED_AUTOGROUP=y
 # CONFIG_SYSFS_DEPRECATED is not set
 CONFIG_RELAY=y
 CONFIG_BLK_DEV_INITRD=y
-CONFIG_INITRAMFS_SOURCE="/sysb"
+CONFIG_INITRAMFS_SOURCE=""
 CONFIG_INITRAMFS_ROOT_UID=0
 CONFIG_INITRAMFS_ROOT_GID=0
 CONFIG_RD_GZIP=y

sysa/linux-4.9.10/linux-4.9.10.sh

@@ -41,14 +41,6 @@ src_prepare() {
 }
 
 src_compile() {
-    # Generate the initramfs so we can remove /sysb
-    make ARCH=i386 prepare
-    make ARCH=i386 usr/
-    mkdir -p "${PREFIX}/boot"
-    mv usr/initramfs_data.cpio.gz "${PREFIX}/boot/initramfs-sysb"
-    make clean
-    rm -rf /sysb
-    sed -i 's:/sysb::' .config
     cp .config include/config/auto.conf
     rm include/generated/autoconf.h
     generate_autoconf_h
@@ -58,5 +50,8 @@ src_compile() {
 }
 
 src_install() {
+    mkdir -p "${PREFIX}/boot"
     cp arch/i386/boot/bzImage "${PREFIX}/boot/linux-4.9.10"
+    cp usr/gen_init_cpio "${PREFIX}/bin"
+    cp scripts/gen_initramfs_list.sh "${PREFIX}/bin"
 }

sysa/linux-4.9.10/patches/initramfs_list.patch

@@ -0,0 +1,17 @@
+SPDX-FileCopyrightText: 2021 fosslinux <fosslinux@aussies.space>
+
+SPDX-License-Identifier: GPL-2.0-only
+
+Use gen_initramfs_list.sh from outside kernel source tree.
+
+--- scripts/gen_initramfs_list.sh	2021-10-10 20:37:12.220231015 +1100
++++ scripts/gen_initramfs_list.sh	2021-10-10 20:37:22.694296140 +1100
+@@ -310,7 +310,7 @@
+ 			fi
+ 		fi
+ 		cpio_tfile="$(mktemp ${TMPDIR:-/tmp}/cpiofile.XXXXXX)"
+-		usr/gen_init_cpio $timestamp ${cpio_list} > ${cpio_tfile}
++		gen_init_cpio $timestamp ${cpio_list} > ${cpio_tfile}
+ 	else
+ 		cpio_tfile=${cpio_file}
+ 	fi

sysa/run.sh

@@ -22,10 +22,14 @@ create_sysb() {
     echo "Creating sysb rootfs"
     mkdir -p /sysb/usr
     for d in bin include lib libexec sbin share; do
-        cp -r "${PREFIX}/${d}" "/sysb/usr/${d}"
+        # Minimise RAM (storage) use - use hard links
+        cp -rl "${PREFIX}/${d}" "/sysb/usr/${d}"
     done
     cp "${SOURCES}/bootstrap.cfg" /sysb/usr/src/bootstrap.cfg
     populate_device_nodes /sysb
+    echo "Creating sysb initramfs"
+    gen_initramfs_list.sh -o "${PREFIX}/boot/initramfs-sysb.cpio.gz" /sysb
+    rm -rf /sysb # Cleanup
 }
 
 go_sysb() {
@@ -35,7 +39,7 @@ go_sysb() {
     # kexec time
     echo "Loading kernel + sysb initramfs using kexec"
     kexec -l "${PREFIX}/boot/linux-4.9.10" --console-serial \
-        --initrd="${PREFIX}/boot/initramfs-sysb" \
+        --initrd="${PREFIX}/boot/initramfs-sysb.cpio.gz" \
         --append="init=/init console=ttyS0"
     echo "kexecing into sysb"
     kexec -e
@@ -237,10 +241,9 @@ rm -rf "${SOURCES}/mes"
 if [ "${CHROOT}" = False ]; then
     build kexec-tools-2.0.22
 
-    create_sysb
-
     build linux-4.9.10
 
+    create_sysb
     go_sysb
 fi