linux: add --linux-source-dir to have custom linux source dir

README.adoc

@@ -561,7 +561,7 @@ To modify the Linux kernel, build and use it as usual:
 For gem5, do:
 
 ....
-git submodule update --init --depth 1 "$(./getvar linux_src_dir)"
+git submodule update --init --depth 1 "$(./getvar linux_source_dir)"
 sudo apt-get install qemu-utils
 ./build-gem5
 ./run --gem5 --prebuilt
@@ -3491,14 +3491,14 @@ Overview: https://stackoverflow.com/questions/50364863/how-to-get-graphical-gui-
 More concretely:
 
 ....
-git -C "$(./getvar linux_src_dir)" fetch https://gem5.googlesource.com/arm/linux gem5/v4.15:gem5/v4.15
-git -C "$(./getvar linux_src_dir)" checkout gem5/v4.15
+git -C "$(./getvar linux_source_dir)" fetch https://gem5.googlesource.com/arm/linux gem5/v4.15:gem5/v4.15
+git -C "$(./getvar linux_source_dir)" checkout gem5/v4.15
 ./build-linux \
   --arch arm \
-  --custom-config-file "$(./getvar linux_src_dir)/arch/arm/configs/gem5_defconfig" \
+  --custom-config-file "$(./getvar linux_source_dir)/arch/arm/configs/gem5_defconfig" \
   --linux-build-id gem5-v4.15 \
 ;
-git -C "$(./getvar linux_src_dir)" checkout -
+git -C "$(./getvar linux_source_dir)" checkout -
 ./run --arch arm --gem5 --linux-build-id gem5-v4.15
 ....
 
@@ -3566,15 +3566,15 @@ Tested on: link:http://github.com/cirosantilli/linux-kernel-module-cheat/commit/
 For `aarch64` we also need to configure the kernel with link:linux_config/display[]:
 
 ....
-git -C "$(./getvar linux_src_dir)" fetch https://gem5.googlesource.com/arm/linux gem5/v4.15:gem5/v4.15
-git -C "$(./getvar linux_src_dir)" checkout gem5/v4.15
+git -C "$(./getvar linux_source_dir)" fetch https://gem5.googlesource.com/arm/linux gem5/v4.15:gem5/v4.15
+git -C "$(./getvar linux_source_dir)" checkout gem5/v4.15
 ./build-linux \
   --arch aarch64 \
   --config-fragment linux_config/display \
-  --custom-config-file "$(./getvar linux_src_dir)/arch/arm64/configs/gem5_defconfig" \
+  --custom-config-file "$(./getvar linux_source_dir)/arch/arm64/configs/gem5_defconfig" \
   --linux-build-id gem5-v4.15 \
 ;
-git -C "$(./getvar linux_src_dir)" checkout -
+git -C "$(./getvar linux_source_dir)" checkout -
 ./run --arch aarch64 --gem5 --linux-build-id gem5-v4.15
 ....
 
@@ -3590,15 +3590,15 @@ The key option to enable support in Linux is `DRM_MALI_DISPLAY=y` which we enabl
 
 ....
 ./build-linux
-git -C "$(./getvar linux_src_dir)" fetch https://gem5.googlesource.com/arm/linux gem5/v4.15:gem5/v4.15
-git -C "$(./getvar linux_src_dir)" checkout gem5/v4.15
+git -C "$(./getvar linux_source_dir)" fetch https://gem5.googlesource.com/arm/linux gem5/v4.15:gem5/v4.15
+git -C "$(./getvar linux_source_dir)" checkout gem5/v4.15
 ./build-linux \
   --arch aarch64 \
   --config-fragment linux_config/display \
-  --custom-config-file "$(./getvar linux_src_dir)/arch/arm64/configs/gem5_defconfig" \
+  --custom-config-file "$(./getvar linux_source_dir)/arch/arm64/configs/gem5_defconfig" \
   --linux-build-id gem5-v4.15 \
 ;
-git -C "$(./getvar linux_src_dir)" checkout -
+git -C "$(./getvar linux_source_dir)" checkout -
 ./run --arch aarch64 --dp650 --gem5 --linux-build-id gem5-v4.15
 ....
 
@@ -4139,7 +4139,7 @@ cat /proc/version
 or in the source:
 
 ....
-cd "$(./getvar linux_src_dir)"
+cd "$(./getvar linux_source_dir)"
 git log | grep -E '    Linux [0-9]+\.' | head
 ....
 
@@ -11415,12 +11415,12 @@ If you want to keep two builds around, one for the latest Linux version, and the
 ./build-linux
 
 # Build another branch.
-git -C "$(./getvar linux_src_dir)" fetch --tags --unshallow
-git -C "$(./getvar linux_src_dir)" checkout v4.16
+git -C "$(./getvar linux_source_dir)" fetch --tags --unshallow
+git -C "$(./getvar linux_source_dir)" checkout v4.16
 ./build-linux --linux-build-id v4.16
 
 # Restore master.
-git -C "$(./getvar linux_src_dir)" checkout -
+git -C "$(./getvar linux_source_dir)" checkout -
 
 # Run master.
 ./run
@@ -11921,7 +11921,7 @@ This example is based on the Linux kernel, for which we used to have patches, bu
 # Last point before out patches.
 last_mainline_revision=v4.15
 next_mainline_revision=v4.16
-cd "$(./getvar linux_src_dir)"
+cd "$(./getvar linux_source_dir)"
 
 # Create a branch before the rebase in case things go wrong.
 git checkout -b "lkmc-${last_mainline_revision}"

build-linux

@@ -58,7 +58,7 @@ Configure the kernel, but don't build it.
         gcc = common.get_toolchain_tool(tool)
         prefix = gcc[:-len(tool)]
         common_args = {
-            'cwd': common.linux_src_dir,
+            'cwd': common.linux_source_dir,
         }
         ccache = shutil.which('ccache')
         if ccache is not None:
@@ -99,7 +99,7 @@ Configure the kernel, but don't build it.
         )
         common.run_cmd(
             [
-                os.path.join(common.linux_src_dir, 'scripts', 'kconfig', 'merge_config.sh'), common.Newline,
+                os.path.join(common.linux_source_dir, 'scripts', 'kconfig', 'merge_config.sh'), common.Newline,
                 '-m', common.Newline,
                 '-O', build_dir, common.Newline,
                 os.path.join(build_dir, '.config'), common.Newline,

common.py

@@ -48,10 +48,8 @@ submodules_dir = os.path.join(root_dir, 'submodules')
 buildroot_src_dir = os.path.join(submodules_dir, 'buildroot')
 crosstool_ng_src_dir = os.path.join(submodules_dir, 'crosstool-ng')
 crosstool_ng_supported_archs = set(['arm', 'aarch64'])
-linux_src_dir = os.path.join(submodules_dir, 'linux')
 linux_config_dir = os.path.join(common.root_dir, 'linux_config')
 rootfs_overlay_dir = os.path.join(common.root_dir, 'rootfs_overlay')
-extract_vmlinux = os.path.join(linux_src_dir, 'scripts', 'extract-vmlinux')
 qemu_src_dir = os.path.join(submodules_dir, 'qemu')
 parsec_benchmark_src_dir = os.path.join(submodules_dir, 'parsec-benchmark')
 ccache_dir = os.path.join('/usr', 'lib', 'ccache')
@@ -316,6 +314,12 @@ Use the docker download Ubuntu root filesystem instead of the default Buildroot
         '--linux-build-dir',
         help='Select the directory that contains the Linux kernel build. Overrides linux-build-id.'
     )
+    parser.add_argument(
+        '--linux-source-dir',
+        help='''\
+Use the given directory as the Linux source tree.
+'''
+    )
     parser.add_argument(
         '--machine',
         help='''Machine type.
@@ -859,6 +863,11 @@ def setup(parser):
     common.run_cmd_file = os.path.join(common.run_dir, 'run.sh')
 
     # Linux
+    if args.linux_source_dir is None:
+        common.linux_source_dir = os.path.join(submodules_dir, 'linux')
+    else:
+        common.linux_source_dir = args.linux_source_dir
+    common.extract_vmlinux = os.path.join(linux_source_dir, 'scripts', 'extract-vmlinux')
     common.linux_buildroot_build_dir = os.path.join(common.buildroot_build_build_dir, 'linux-custom')
     if args.linux_build_dir is None:
         common.linux_build_dir = os.path.join(common.out_dir, 'linux', args.linux_build_id, args.arch)