Automate failed gem5 x86 attempt

build

@@ -37,14 +37,17 @@ case "$arch" in
   x86_64)
     defconfig=qemu_x86_64_defconfig
   ;;
+  x86_64-gem5)
+    defconfig=qemu_x86_64_defconfig
+  ;;
   arm)
     # qemu_arm_vexpress_defconfig required a newer QEMU than 2.0.0 on a Ubuntu host.
     # so let's stick to versatile for now.
     defconfig=qemu_arm_versatile_defconfig
   ;;
   arm-gem5)
-    # qemu_arm_vexpress_defconfig required a newer QEMU than 2.0.0 on a Ubuntu host.
-    # so let's stick to versatile for now.
+    # Ideally we should use a custom clean config here.
+    # But let's just use this one as a starting point for now.
     defconfig=qemu_arm_versatile_defconfig
     post_script_args="$post_script_args -n"
   ;;
@@ -67,9 +70,9 @@ make O="$outdir" BR2_EXTERNAL="$(pwd)/../kernel_module" "$defconfig"
 # TODO Can't get rid of this for now.
 # http://stackoverflow.com/questions/44078245/is-it-possible-to-use-config-fragments-with-buildroots-config
 cat ../buildroot_config_fragment >> "${outdir}/.config"
-if [ "$arch" = 'arm-gem5' ]; then
+if echo "$arch" | grep -Eq -- '-gem5$'; then
   echo "\
-BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE=\"../kernel_config_gem5\"
+BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE=\"../kernel_config_${arch}\"
 " >> "${outdir}/.config"
 else
   echo "\
@@ -99,6 +102,6 @@ time \
   all \
 ;
 cd ..
-if [ "$arch" = 'arm-gem5' ]; then
-  ./build-gem5
+if echo "$arch" | grep -Eq -- '-gem5$'; then
+  ./build-gem5 -a "$arch"
 fi

build-gem5

@@ -1,18 +1,38 @@
 #/usr/bin/env bash
-set -e
+set -eu
+arch='arm-gem5'
+while getopts 'a:' OPT; do
+  case "$OPT" in
+    a)
+      arch="$OPTARG"
+      ;;
+  esac
+done
+shift "$(($OPTIND - 1))"
 if [ ! -d 'gem5' ]; then
-    git clone https://gem5.googlesource.com/public/gem5
+  git clone https://gem5.googlesource.com/public/gem5
 fi
 cd gem5
 git checkout da79d6c6cde0fbe5473ce868c9be4771160a003b
-# Compilation fails with gcc 7 on that commit.
-# There were some recent portability patches, so it will likely get there soon.
-CC=gcc-6 CXX=g++-6 scons -j"$(nproc)" --ignore-style build/ARM/gem5.opt
-make -C system/arm/dt
-make -C system/arm/simple_bootloader
-make -C system/arm/aarch64_bootloader/
-# TODO use local paths. The search path can be changed with M5_PATH="$(pwd)",
-# but the annoying "binaries/" is added in front of it.
-mkdir -p ../gem5-system/binaries
-cp ./system/arm/simple_bootloader/boot_emm.arm ../gem5-system/binaries
-cp ./system/arm/aarch64_bootloader/boot_emm.arm64 ../gem5-system/binaries
+system_dir='../gem5-system'
+binaries_dir="${system_dir}/binaries"
+disks_dir="${system_dir}/disks"
+mkdir -p "$binaries_dir" "$disks_dir"
+if [ "$arch" = 'x86_64-gem5' ]; then
+  CC=gcc-6 CXX=g++-6 scons -j"$(nproc)" --ignore-style build/X86/gem5.opt
+  f="${disks_dir}/linux-bigswap2.img"
+  dd if=/dev/zero of="$f" bs=1024 count=65536
+  mkswap "$f"
+  # This file must always be present, despite --kernel overriding that default and selecting the kernel.
+  # I'm not even joking. No one has ever built x86 gem5 without the magic dist dir present.
+  touch "${binaries_dir}/x86_64-vmlinux-2.6.22.9"
+elif [ "$arch" = 'arm-gem5' ]; then
+  # Compilation fails with gcc 7 on that commit.
+  # There were some recent portability patches, so it will likely get there soon.
+  CC=gcc-6 CXX=g++-6 scons -j"$(nproc)" --ignore-style build/ARM/gem5.opt
+  make -C system/arm/dt
+  make -C system/arm/simple_bootloader
+  make -C system/arm/aarch64_bootloader/
+  cp ./system/arm/simple_bootloader/boot_emm.arm "$binaries_dir"
+  cp ./system/arm/aarch64_bootloader/boot_emm.arm64 "$binaries_dir"
+fi

gem5.md

@@ -27,7 +27,7 @@ Vs QEMU:
 ## ARM
 
     ./configure && ./build -a arm-gem5
-    ./rungem5
+    ./rungem5 -a arm-gem5
 
 On another shell:
 
@@ -92,8 +92,28 @@ Related threads:
 
 - <https://www.mail-archive.com/gem5-users@gem5.org/msg11384.html>
 - <https://stackoverflow.com/questions/37906425/booting-gem5-x86-ubuntu-full-system-simulation>
+- <http://www.lowepower.com/jason/creating-disk-images-for-gem5.html> claims to have a working config for x86_64 kernel 4.8.13
 
-### Working baseline
+### Our best attempt
+
+    ./configure && ./build -a x86_64-gem5
+    ./rungem5 -a x86_64-gem5
+
+telnet:
+
+    i8042: PNP: No PS/2 controller found.
+    i8042: Probing ports directly.
+    Connection closed by foreign host.
+
+stdout:
+
+    panic: Data written for unrecognized command 0xd1
+    Memory Usage: 1235908 KBytes
+    Program aborted at tick 427627410500
+
+The same failure happens if we use the working QEMU Linux kernel, and / or if we use the kernel 4.8.13 as proposed in lowepower's post..
+
+### Working baseline with magic image
 
 Working x86 with the pre-built magic image with an ancient 2.6.22.9 kernel starting point:
 
@@ -124,7 +144,7 @@ On another shell:
 
     telnet localhost 3456
 
-### Unmodified Buildroot images
+### Unmodified Buildroot images 2
 
 bzImage fails, so we always try with vmlinux obtained from inside build/.
 

rungem5

@@ -1,11 +1,35 @@
 #!/usr/bin/env bash
-outdir="$(pwd)/buildroot/output.arm-gem5~"
-M5_PATH="$(pwd)/gem5-system" \
+arch='arm-gem5'
+while getopts 'a:' OPT; do
+  case "$OPT" in
+    a)
+      arch="$OPTARG"
+      ;;
+  esac
+done
+shift "$(($OPTIND - 1))"
+outdir="$(pwd)/buildroot/output.${arch}~"
+echo $arch
+if echo "$arch" | grep -Eq '^x86_64(-|$)'; then
+  cmd="\
+M5_PATH=\"$(pwd)/gem5-system\" \
+./gem5/build/X86/gem5.opt \
+gem5/configs/example/fs.py \
+--disk-image=\"${outdir}/images/rootfs.ext2\" \
+--kernel=\"${outdir}/build/linux-custom/vmlinux\" \
+--root-device='/dev/sda' \
+"
+elif echo "$arch" | grep -Eq '^arm-'; then
+  cmd="\
+M5_PATH=\"$(pwd)/gem5-system\" \
 ./gem5/build/ARM/gem5.opt \
-  gem5/configs/example/fs.py \
-  --disk-image="${outdir}/images/rootfs.ext2" \
-  --dtb-file="$(pwd)/gem5/system/arm/dt/armv7_gem5_v1_1cpu.dtb" \
-  --kernel="${outdir}/build/linux-custom/vmlinux" \
-  --machine-type='VExpress_GEM5_V1' \
-  --root-device='/dev/sda' \
-;
+gem5/configs/example/fs.py \
+--disk-image=\"${outdir}/images/rootfs.ext2\" \
+--dtb-file=\"$(pwd)/gem5/system/arm/dt/armv7_gem5_v1_1cpu.dtb\" \
+--kernel=\"${outdir}/build/linux-custom/vmlinux\" \
+--machine-type='VExpress_GEM5_V1' \
+--root-device='/dev/sda' \
+"
+fi
+echo "$cmd"
+eval "$cmd"