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expand common options
This commit is contained in:
Ciro Santilli
65
README.adoc
65
README.adoc
@@ -238,10 +238,10 @@ For the most part, if you just add the `--gem5` option or `-gem5` suffix to all
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....
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./configure --gem5 && \
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./build --arch aarch64 --gem5 && \
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./build-gem5 --arch aarch64 && \
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./run --arch aarch64 --gem5 \
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;
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./build --arch aarch64 --gem5 && \
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./build-gem5 --arch aarch64 && \
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./run --arch aarch64 --gem5 &&\
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:;
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....
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If you have already built <<qemu-buildroot-setup>> previously, don't be afraid, gem5 and QEMU use almost the same root filesystem and kernel, so `./build --gem` will be fast. It is currently only needed for the <<m5>> tool.
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@@ -708,9 +708,12 @@ For `aarch64` we also need `-c kernel_config_fragment/display`:
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....
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git -C "$(./getvar linux_src_dir)" checkout gem5/v4.15
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./build -gl --arch aarch64 \
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./build \
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--arch aarch64 \
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-c kernel_config_fragment/display \
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--gem5 \
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-K linux/arch/arm64/configs/gem5_defconfig \
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-l \
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--linux-build-id gem5-v4.15 \
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;
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git -C "$(./getvar linux_src_dir)" checkout -
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@@ -1315,7 +1318,7 @@ First shell:
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Another shell:
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....
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./run -n 1
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./run --run-id 1
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....
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and now you have two QEMU instances running in parallel.
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@@ -1330,22 +1333,22 @@ Our scripts solve two difficulties with simultaneous runs:
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Each run gets a separate output directory. For example:
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....
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./run --arch aarch64 --gem5 -n 0 &>/dev/null &
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./run --arch aarch64 --gem5 -n 1 &>/dev/null &
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./run --arch aarch64 --gem5 --run-id 0 &>/dev/null &
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./run --arch aarch64 --gem5 --run-id 1 &>/dev/null &
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....
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produces two separate `m5out` directories:
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....
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echo "$(./getvar --arch aarch64 --gem5 -n 0 m5out_dir)"
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echo "$(./getvar --arch aarch64 --gem5 -n 1 m5out_dir)"
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echo "$(./getvar --arch aarch64 --gem5 --run-id 0 m5out_dir)"
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echo "$(./getvar --arch aarch64 --gem5 --run-id 1 m5out_dir)"
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....
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and the gem5 host executable stdout and stderr can be found at:
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....
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less "$(./getvar --arch aarch64 --gem5 -n 0 termout_file)"
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less "$(./getvar --arch aarch64 --gem5 -n 1 termout_file)"
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less "$(./getvar --arch aarch64 --gem5 --run-id 0 termout_file)"
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less "$(./getvar --arch aarch64 --gem5 --run-id 1 termout_file)"
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....
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Each line is prepended with the timestamp in seconds since the start of the program when it appeared.
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@@ -1353,7 +1356,7 @@ Each line is prepended with the timestamp in seconds since the start of the prog
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To have more semantic output directories names for later inspection, you can use a non numeric string for the run ID, and indicate the port offset explicitly:
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....
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./run --arch aarch64 --gem5 -n some-experiment --port-offset 1
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./run --arch aarch64 --gem5 --run-id some-experiment --port-offset 1
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....
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`--port-offset` defaults to the run ID when that is a number.
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@@ -1361,8 +1364,8 @@ To have more semantic output directories names for later inspection, you can use
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Like <<cpu-architecture>>, you will need to pass the `-n` option to anything that needs to know runtime information, e.g. <<gdb>>:
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....
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./run -n 1
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./rungdb -n 1
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./run --run-id 1
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./rungdb --run-id 1
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....
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To run multiple gem5 checkouts, see: <<gem5-simultaneous-runs-with-build-variants>>.
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@@ -7527,8 +7530,8 @@ List all available debug flags:
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but to understand most of them you have to look at the source code:
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....
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less gem5/gem5/src/cpu/SConscript
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less gem5/gem5/src/cpu/exetrace.cc
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less "$(./getvar gem5_src_dir)/src/cpu/SConscript"
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less "$(./getvar gem5_src_dir)/src/cpu/exetrace.cc"
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....
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As can be seen on the `Sconstruct`, `Exec` is just an alias that enables a set of flags.
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@@ -8781,13 +8784,13 @@ TODO We didn't manage to find a working ARM analogue to <<rdtsc>>: link:packages
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=== gem5 Python scripts without rebuild
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We have made a crazy setup that allows you to just `cd` into `gem5/gem5`, and edit Python scripts directly there.
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We have made a crazy setup that allows you to just `cd` into `submodules/gem5`, and edit Python scripts directly there.
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This is not normally possible with Buildroot, since normal Buildroot packages first copy files to the output directory (`$(./getvar -a <arch> build_dir)/<pkg>`), and then build there.
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So if you modified the Python scripts with this setup, you would still need to `./build` to copy the modified files over.
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For gem5 specifically however, we have hacked up the build so that we `cd` into the `gem5/gem5` tree, and then do an link:https://www.mail-archive.com/gem5-users@gem5.org/msg15421.html[out of tree] build to `out/common/gem5`.
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For gem5 specifically however, we have hacked up the build so that we `cd` into the `submodules/gem5` tree, and then do an link:https://www.mail-archive.com/gem5-users@gem5.org/msg15421.html[out of tree] build to `out/common/gem5`.
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Another advantage of this method is the we factor out the `arm` and `aarch64` gem5 builds which are identical and large, as well as the smaller arch generic pieces.
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@@ -8807,7 +8810,7 @@ The `--gem5-biglittle` option enables the alternative `configs/example/arm/fs_bi
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First apply:
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....
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patch -d gem5/gem5 -p1 < patches/manual/gem5-biglittle.patch
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patch -d "$(./getvar gem5_src_dir)" -p 1 < patches/manual/gem5-biglittle.patch
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....
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then:
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@@ -9014,13 +9017,11 @@ This approach has the advantage of being simple and robust, but it wastes a lot
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The next less coarse approach, is to use the `-s` option:
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....
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./build -s mybranch
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./build --suffix mybranch
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....
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which generates a full new build under `out/` named for example as `out/x86_64-mybranch`, but at least avoids copying up the source.
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TODO: only `-s` works for `./build`, e.g. if you want to `./run` afterwards you need to manually `mv` build around. This should be easy to patch however.
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==== Linux kernel build variants
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Since the Linux kernel is so important to us, we have created a convenient dedicated mechanism for it.
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@@ -9051,10 +9052,10 @@ Analogous to the <<linux-kernel-build-variants>> but with the `-Q` option instea
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....
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./build-qemu
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git -C "$(./getvar qemu_src_dir)" checkout v2.12.0
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./build-qemu -Q v2.12.0
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./build-qemu --qemu-build-id v2.12.0
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git -C "$(./getvar qemu_src_dir)" checkout -
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./run
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./run -Q v2.12.0
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./run --qemu-build-id v2.12.0
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....
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==== gem5 build variants
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@@ -9063,12 +9064,10 @@ Analogous to the <<linux-kernel-build-variants>> but with the `-M` option instea
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....
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# Build master.
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./build --gem5
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./build-gem5
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# Build another branch.
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git -C "$(./getvar gem5_src_dir)" checkout some-branch
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./build --gem5 --gem5-build-id some-branch
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./build-gem5 --gem5-build-id some-branch
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# Restore master.
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@@ -9094,23 +9093,21 @@ In order to checkout multiple gem5 builds and run them simultaneously, you also
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....
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# Build master.
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./build --gem5
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./build-gem5
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# Build another branch.
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git -C "$(./getvar linux_src_dir)" checkout some-branch
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./build --gem5 --gem5-build-id some-branch --gem5-worktree some-branch
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./build-gem5 --gem5-build-id some-branch --gem5-worktree some-branch
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# Restore master.
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git -C "$(./getvar linux_src_dir)" checkout -
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# Run master.
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./run --gem5 -n 0 &>/dev/null &
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./run --gem5 --run-id 0 &>/dev/null &
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# Run another branch using the worktree for the scripts,
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# without the need to check out anything.
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./run --gem5 --gem5-build-id some-branch --gem5-worktree some-branch -n 1 &>/dev/null &
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./run --gem5 --gem5-build-id some-branch --gem5-worktree some-branch --run-id 1 &>/dev/null &
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....
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When `--gem5-worktree` is not given, the default source tree under `submodules/gem5` is used.
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@@ -9143,8 +9140,8 @@ git -C data/gem5/some-branch checkout some-branch-v2
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Built and run `gem5.debug`, which has optimizations turned off unlike the default `gem5.opt`:
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....
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./build --arch aarch64 --gem5 --gem5-build-id debug -t debug
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./run --arch aarch64 --gem5 --gem5-build-id debug -t debug
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./build-gem5 --arch aarch64 --gem5-build-id debug --gem5-build-type debug
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./run --arch aarch64 --gem5 --gem5-build-id debug --gem5-build-type debug
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....
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We generate a separate build folder with `--gem5-build-id` just to prevent the `opt` build from getting overwritten, so we can keep both around at the same time.
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@@ -9153,7 +9150,7 @@ A Linux kernel boot was about 14 times slower than opt at 71e927e63bda6507d5a528
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....
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./run --arch aarch64 --eval 'm5 exit' --gem5 --linux-build-id v4.16
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./run --arch aarch64 --eval 'm5 exit' --gem5 --linux-build-id v4.16 --gem5-build-id debug -t debug
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./run --arch aarch64 --eval 'm5 exit' --gem5 --linux-build-id v4.16 --gem5-build-id debug --gem5-build-type debug
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....
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Therefore the performance different is very big, making debug mode almost unusable.
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