Update GEM5 to master to fix x86 boot via 3feeb994ae613fd6b3734c1a991285b2ecbd1946

See also: http://gem5-users.gem5.narkive.com/CQh9J6fU/fail-to-run-fs-mode-with-linux-kernel-v4-8-13-and-ubuntu-image-16-04-1

Start sketching how to tweak system parameters, number of CPUs works, caches don't.

run

@@ -4,6 +4,7 @@ set -e
 
 # CLI handling.
 arch=x86_64
+cpus=1
 debug_vm=''
 kgdb=false
 nographic=false
@@ -17,11 +18,14 @@ gem5=false
 gem5opts=''
 initrd=false
 root=''
-while getopts a:Dde:G:giknt:x OPT; do
+while getopts a:c:Dde:G:giknt:x OPT; do
   case "$OPT" in
     a)
       arch="$OPTARG"
       ;;
+    c)
+      cpus="$OPTARG"
+      ;;
     d)
       extra_flags="$extra_flags -S -s"
       ;;
@@ -66,9 +70,10 @@ M5_PATH='$(pwd)/gem5/gem5-system' \
 '${gem5_dir}/build/X86/gem5.opt' \
 ${gem5opts} \
 '${gem5_dir}/configs/example/fs.py' \
+--command-line='earlyprintk=ttyS0 console=ttyS0 lpj=7999923 root=/dev/hda $extra_append' \
 --disk-image='${outdir}/images/rootfs.ext2' \
 --kernel='${outdir}/build/linux-custom/vmlinux' \
---root-device=/dev/sda \
+--num-cpus=${cpus} \
 $extra_flags \
 "
   elif [ "$arch" = arm ] || [ "$arch" = aarch64 ]; then
@@ -80,9 +85,10 @@ ${gem5opts} \
 '${gem5_dir}/configs/example/fs.py' \
 --command-line='earlyprintk=pl011,0x1c090000 console=ttyAMA0 lpj=19988480 rw loglevel=8 mem=512MB root=/dev/sda $extra_append' \
 --disk-image='${outdir}/images/rootfs.ext2' \
---dtb-file='${gem5_dir}/system/arm/dt/$([ "$arch" = arm ] && echo armv7_gem5_v1_1cpu || echo armv8_gem5_v1_1cpu).dtb' \
+--dtb-file='${gem5_dir}/system/arm/dt/$([ "$arch" = arm ] && echo "armv7_gem5_v1_${cpus}cpu" || echo "armv8_gem5_v1_${cpus}cpu").dtb' \
 --kernel='${outdir}/build/linux-custom/vmlinux' \
 --machine-type=VExpress_GEM5_V1 \
+--num-cpus=${cpus} \
 $extra_flags \
 "
   fi
@@ -95,7 +101,7 @@ $buildroot_out_dir/host/usr/bin/qemu-system-${arch} \
 -m 128M \
 -monitor telnet::45454,server,nowait \
 -netdev user,hostfwd=tcp::45455-:45455,id=net0 \
--smp 1 \
+-smp $cpus \
 "
   if $initrd; then
     extra_flags="$extra_flags -initrd '${images_dir}/rootfs.cpio'"