diff --git a/scripts/mkroot.sh b/scripts/mkroot.sh
index 3e8d35b..ade50a0 100755
--- a/scripts/mkroot.sh
+++ b/scripts/mkroot.sh
@@ -1,60 +1,60 @@
 #!/bin/bash
 
 # Clear environment variables by restarting script w/bare minimum passed through
-# set ALL= LINUX= CROSS= on command line
 [ -z "$NOCLEAR" ] && exec env -i NOCLEAR=1 HOME="$HOME" PATH="$PATH" \
-    CROSS_COMPILE="$CROSS_COMPILE" "$0" "$@"
+    "LINUX=$LINUX" "CROSS=$CROSS" CROSS_COMPILE="$CROSS_COMPILE" "$0" "$@"
 
-die() { echo "$@" >&2; exit 1; }
-announce() { echo -e "\033]2;$CROSS $*\007\n=== $*"; }
-getcross() { X="$(echo "$CCC/$1"-*cross/bin/"$1"*-cc)"; echo "${X%cc}"; }
-
-# assign command line NAME=VALUE args to env vars
+# assign command line NAME=VALUE args to env vars, keeping rest as packages
 while [ $# -ne 0 ]; do
   [ "${1/=/}" != "$1" ] && eval "export ${1/=*/}=\"\${1#*=}\"" ||
     { [ "$1" != '--' ] && PKG="${PKG:-plumbing} $1"; }
   shift
 done
 
-# set output and work directories (can override on cmdline)
+die() { echo "$@" >&2; exit 1; }
+announce() { echo -e "\033]2;$CROSS $*\007\n=== $*"; }
+
+# Create target-independent working directories (cmdline can change locations)
 TOP="$PWD/root"
 mkdir -p ${BUILD:=$TOP/build} ${AIRLOCK:=$TOP/airlock} ${LOG:=$TOP/log} ||exit 1
 
 # set CROSS_COMPILE from $CROSS using ccc. Handle "all" w/log, list, and err chk
 if [ ! -z "$CROSS" ]; then
   [ ! -d "${CCC:=$PWD/ccc}" ] && die "No ccc symlink to compiler directory."
-  if [ "$CROSS" == all ]; then
+  CROSS_COMPILE="$(echo "$CCC/$CROSS"-*cross/bin/"$CROSS"*-cc | sed 's/cc$//')"
+  if [ "${CROSS::3}" == all ]; then
     for i in $(ls "$CCC" | sed -n 's/-.*//p' | sort -u | xargs); do
       { rm -f "$LOG/$i-log".{failed,success}
         "$0" "$@" CROSS=$i ; [ $((X=$?)) -eq 0 ] && mv "$LOG/$i".{txt,success}
       } |& tee "$LOG/$i.txt"
       [ ! -e "$LOG/$i.success" ] &&
-        { mv "$LOG/$i".{txt,failed};[ -z "$ALL" ] && exit 1; }
-    done; exit
-  elif [ ! -e "${CROSS_COMPILE:=$(getcross $CROSS)}cc" ]; then
-    ls "$CCC" | sed -n 's/-.*//p' | sort -u | xargs; exit
+        { mv "$LOG/$i".{txt,failed};[ "$CROSS" != allnonstop ] && exit 1; }
+    done
+    exit
+  elif [ ! -e "${CROSS_COMPILE}cc" ]; then
+    ls "$CCC" | sed -n 's/-.*//p' | sort -u | xargs
+    exit
   fi
 fi
 
-# Digest $CROSS_COMPILE (if any) into appropriate environment variables.
-if [ -z "$CROSS_COMPILE" ]; then
-  if ! cc --static -xc - -o /dev/null <<< "int main(void) {return 0;}"; then
-    echo "Warning: host compiler can't create static binaries." >&2; sleep 3
-  fi
-else
+${CROSS_COMPILE}cc --static -xc - -o /dev/null <<< "int main(void){return 0;}"||
+  die "${CROSS_COMPILE}cc can't create static binaries"
+
+# Parse and sanity check $CROSS_COMPILE (if any)
+if [ ! -z "$CROSS_COMPILE" ]; then
   CROSS_PATH="$(dirname "$(which "${CROSS_COMPILE}cc")")"
-  CROSS_BASE="$(basename "$CROSS_COMPILE")"
   [ -z "$CROSS_PATH" ] && die "no ${CROSS_COMPILE}cc in path"
-  : ${CROSS:=${CROSS_BASE/-*/}}
+  : ${CROSS_BASE:=$(basename "$CROSS_COMPILE")} ${CROSS:=${CROSS_BASE/-*/}}
 fi
 echo "Building for ${CROSS:=host}"
 
+# Create target-specific work/output directories
 : ${OUTPUT:=$TOP/$CROSS} ${PKGDIR:=$PWD/scripts/root}
-[ -z "$ROOT" ] && ROOT="$OUTPUT/fs" && rm -rf "$ROOT"
 MYBUILD="$BUILD/${CROSS_BASE:-host-}tmp"
 rm -rf "$MYBUILD" && mkdir -p "$MYBUILD" || exit 1
+[ -z "$ROOT" ] && ROOT="$OUTPUT/fs" && rm -rf "$ROOT" # only blank if NOT set
 
-# Provide known $PATH contents (airlock) for cross compile builds
+# When cross compiling build everything under a host toybox with known behavior
 if [ ! -z "$CROSS_COMPILE" ]; then
   if [ ! -e "$AIRLOCK/toybox" ]; then
     announce "airlock"
@@ -64,11 +64,11 @@
   export PATH="$CROSS_PATH:$AIRLOCK"
 fi
 
-# directory layout
+# Create new root filesystem's directory layout
 mkdir -p "$ROOT"/{etc,tmp,proc,sys,dev,home,mnt,root,usr/{bin,sbin,lib},var} &&
 chmod a+rwxt "$ROOT"/tmp && ln -s usr/{bin,sbin,lib} "$ROOT" || exit 1
 
-# init script. Runs as pid 1 from initramfs to set up and hand off system.
+# Write init script. Runs as pid 1 from initramfs to set up and hand off system.
 cat > "$ROOT"/init << 'EOF' &&
 #!/bin/sh
 
@@ -85,21 +85,20 @@
   chmod +t /dev/shm
 fi
 
-if [ $$ -eq 1 ]; then
-  # Setup networking for QEMU (needs /proc)
+if [ $$ -eq 1 ]; then # Setup networking for QEMU (needs /proc)
   ifconfig lo 127.0.0.1
   ifconfig eth0 10.0.2.15
   route add default gw 10.0.2.2
   [ "$(date +%s)" -lt 1000 ] && timeout 2 sntp -sq 10.0.2.2 # Ask host
   [ "$(date +%s)" -lt 10000000 ] && sntp -sq time.google.com
 
-  # Run expansion scripts (if any)
-  for i in $(echo /etc/rc/* | sort); do [ -e "$i" ] && . $i; done
+  # Run package scripts (if any)
+  [ -e /etc/rc ] && for i in $(echo /etc/rc/* | sort); do . $i; done
 
   [ -z "$CONSOLE" ] && CONSOLE="$(</sys/class/tty/console/active)"
   [ -z "$HANDOFF" ] && HANDOFF=/bin/sh && echo Type exit when done.
   exec oneit -c /dev/"${CONSOLE:-console}" $HANDOFF
-else
+else # for chroot
   /bin/sh
   umount /dev/pts /dev /sys /proc
 fi
@@ -115,13 +114,16 @@
 EOF
 echo -e 'root:x:0:\nguest:x:500:\nnobody:x:65534:' > "$ROOT"/etc/group || exit 1
 
+# Build static toybox with existing .config if there is one, else defconfig+sh
 announce toybox
 [ -e .config ] && CONF=silentoldconfig || unset CONF
 make clean ${CONF:-defconfig KCONFIG_ALLCONFIG=<(echo $'CONFIG_SH=y\nCONFIG_ROUTE=y')} &&
 LDFLAGS=--static PREFIX="$ROOT" make toybox install || exit 1
 
-# Build any modules
-for i in $PKG; do announce "$i"; PATH="$PKGDIR:$PATH" source $i; done
+# Build any packages listed on command line
+for i in $PKG; do
+  announce "$i"; PATH="$PKGDIR:$PATH" source $i; [ $? -ne 0 ] && die $i
+done
 
 if [ -z "$LINUX" ] || [ ! -d "$LINUX/kernel" ]; then
   echo 'No $LINUX directory, kernel build skipped.'
@@ -178,14 +180,14 @@
     KARCH=powerpc QEMU="ppc64 -M pseries -vga none" KARGS=/dev/hvc0
     VMLINUX=vmlinux
     KCONF=PPC64,PPC_PSERIES,CPU_LITTLE_ENDIAN,PPC_OF_BOOT_TRAMPOLINE,BLK_DEV_SD,SCSI_LOWLEVEL,SCSI_IBMVSCSI,ATA,NET_VENDOR_IBM,IBMVETH,HVC_CONSOLE,PPC_TRANSACTIONAL_MEM,PPC_DISABLE_WERROR,SECTION_MISMATCH_WARN_ONLY
-  elif [ "$TARGET" = s390x ] ; then
+  elif [ "$TARGET" = s390x ]; then
     QEMU="s390x" KARCH=s390 VMLINUX=arch/s390/boot/bzImage
     KCONF=MARCH_Z900,PACK_STACK,NET_CORE,VIRTIO_NET,VIRTIO_BLK,SCLP_TTY,SCLP_CONSOLE,SCLP_VT220_TTY,SCLP_VT220_CONSOLE,S390_GUEST
-  elif [ "$TARGET" == sh2eb ] ; then
+  elif [ "$TARGET" == sh2eb ]; then
     KARCH=sh VMLINUX=vmlinux KERNEL_CONFIG='CONFIG_MEMORY_START=0x10000000
-CONFIG_CMDLINE="console=ttyUL0 earlycon"'
+CONFIG_CMDLINE="console=ttyUL0 earlycon"' BUILTIN=1
     KCONF=CPU_SUBTYPE_J2,CPU_BIG_ENDIAN,SH_JCORE_SOC,SMP,BINFMT_ELF_FDPIC,JCORE_EMAC,SERIAL_UARTLITE,SERIAL_UARTLITE_CONSOLE,HZ_100,CMDLINE_OVERWRITE,SPI,SPI_JCORE,MMC,PWRSEQ_SIMPLE,MMC_BLOCK,MMC_SPI
-  elif [ "$TARGET" == sh4 ] ; then
+  elif [ "$TARGET" == sh4 ]; then
     QEMU="sh4 -M r2d -serial null -serial mon:stdio" KARCH=sh
     KARGS="ttySC1 noiotrap" VMLINUX=arch/sh/boot/zImage
     KERNEL_CONFIG="CONFIG_MEMORY_START=0x0c000000"
@@ -194,10 +196,11 @@
   else die "Unknown \$TARGET"
   fi
 
-  if [ ! -z "$QEMU" ] ; then
-    # Write the qemu launch script
+  # Write the qemu launch script
+  if [ ! -z "$QEMU" ]; then
+    [ -z "$BUILTIN" ] && INITRD="-initrd ${CROSS_BASE}root.cpio.gz"
     echo qemu-system-"$QEMU" '"$@"' $QEMU_MORE -nographic -no-reboot -m 256 \
-         "-kernel $(basename "$VMLINUX") -initrd ${CROSS_BASE}root.cpio.gz" \
+         -kernel $(basename $VMLINUX) $INITRD \
          "-append \"quiet panic=1 HOST=$TARGET console=$KARGS \$KARGS\"" \
          ${DTB:+-dtb "$(basename "$DTB")"} ";echo -e '\e[?7h'" \
          > "$OUTPUT/qemu-$TARGET.sh" &&
@@ -214,11 +217,12 @@
     echo "# CONFIG_EMBEDDED is not set"
 
     # Expand list of =y symbols, first generic then architecture-specific
-    for i in EARLY_PRINTK,BINFMT_ELF,BINFMT_SCRIPT,NO_HZ,HIGH_RES_TIMERS,BLK_DEV,BLK_DEV_INITRD,RD_GZIP,BLK_DEV_LOOP,EXT4_FS,EXT4_USE_FOR_EXT2,VFAT_FS,FAT_DEFAULT_UTF8,MISC_FILESYSTEMS,SQUASHFS,SQUASHFS_XATTR,SQUASHFS_ZLIB,DEVTMPFS,DEVTMPFS_MOUNT,TMPFS,TMPFS_POSIX_ACL,NET,PACKET,UNIX,INET,IPV6,NETDEVICES,NET_CORE,NETCONSOLE,ETHERNET,COMPAT_32BIT_TIME $KCONF ; do
+    for i in BINFMT_ELF,BINFMT_SCRIPT,NO_HZ,HIGH_RES_TIMERS,BLK_DEV,BLK_DEV_INITRD,RD_GZIP,BLK_DEV_LOOP,EXT4_FS,EXT4_USE_FOR_EXT2,VFAT_FS,FAT_DEFAULT_UTF8,MISC_FILESYSTEMS,SQUASHFS,SQUASHFS_XATTR,SQUASHFS_ZLIB,DEVTMPFS,DEVTMPFS_MOUNT,TMPFS,TMPFS_POSIX_ACL,NET,PACKET,UNIX,INET,IPV6,NETDEVICES,NET_CORE,NETCONSOLE,ETHERNET,COMPAT_32BIT_TIME,EARLY_PRINTK,IKCONFIG,IKCONFIG_PROC $KCONF ; do
       echo "# architecture ${X:-independent}"
       sed -E '/^$/d;s/([^,]*)($|,)/CONFIG_\1=y\n/g' <<< "$i"
       X=specific
     done
+    [ ! -z "$BUILTIN" ] && echo -e CONFIG_INITRAMFS_SOURCE="\"$OUTPUT/fs\""
     echo "$KERNEL_CONFIG"
   } > "$OUTPUT/miniconfig-$TARGET" &&
   make ARCH=$KARCH allnoconfig KCONFIG_ALLCONFIG="$OUTPUT/miniconfig-$TARGET" &&
@@ -238,7 +242,7 @@
 fi
 
 # clean up and package root filesystem for initramfs.
-rmdir "$MYBUILD" "$BUILD" 2>/dev/null
-announce "${CROSS_BASE}root.cpio.gz"
-(cd "$ROOT" && find . | cpio -o -H newc --no-preserve-owner | gzip) \
-  > "$OUTPUT/$CROSS_BASE"root.cpio.gz
+[ -z "$BUILTIN" ] && announce "${CROSS_BASE}root.cpio.gz" &&
+  (cd "$ROOT" && find . | cpio -o -H newc --no-preserve-owner | gzip) \
+    > "$OUTPUT/$CROSS_BASE"root.cpio.gz
+rmdir "$MYBUILD" "$BUILD" 2>/dev/null # remove if empty