3rd-party/linux-kernel-module-cheat
1
0
Fork 0
mirror of https://github.com/cirosantilli/linux-kernel-module-cheat.git synced 2026-01-23 02:05:57 +01:00
Code Issues Releases Wiki Activity

fs_bigLITTLE: minimized

Browse Source 
I was confused previously by the fact that the DTB is required,
despite gem5 autogenerating a default one if it is not provided.

TODO: why is the generated one not correct?
This commit is contained in:
Ciro Santilli
2018-04-30 18:14:57 +01:00
parent 3e24f56835
commit ea244e1d6f
2 changed files with 17 additions and 43 deletions
Download Patch File Download Diff File Expand all files Collapse all files

49
README.adoc
View File

@@ -4556,56 +4556,19 @@ But then we have to deal specially with the `m5` tool, which has to be cross com
=== gem5 fs_bitLITTLE
TODO integrate into `run`.
This system is more representative of ARM, which almost always has the big little cluster.
If we try `fs_bigLITTLE.py` with our images:
Working from source setup: first hack `fs_bigLITTLE.py` to use `root=vda` insead of `root=vda1`. Then:
....
./out/aarch64/buildroot/build/gem5-1.0/gem5/build/ARM/gem5.opt \
--debug-flags=Exec \
--debug-file=trace.txt \
./out/aarch64/buildroot/build/gem5-1.0/gem5/configs/example/arm/fs_bigLITTLE.py \
--disk="$(pwd)/out/aarch64/buildroot/images/rootfs.ext2" \
--kernel="$(pwd)/out/aarch64/buildroot/build/linux-custom/vmlinux" \
--big-cpus=2 \
--little-cpus=2 \
--caches \
;
./fs-biglittle
....
nothing shows on screen, but `m5out/trace.txt` does go through `start_kernel` and `printk`, so it must also be an output configuration problem. It seems to loop around `memmap_init_zone`.
Boot messages start at 5 minutes, boot finishes at 13 minutes and gives a shell.
After 7 minutes, gem5 exits with `simulate() limit reached @ 18446744073709551615`.
First we check that the magic images work:
....
./out/aarch64/buildroot/build/gem5-1.0/gem5/build/ARM/gem5.opt \
./out/aarch64/buildroot/build/gem5-1.0/gem5/configs/example/arm/fs_bigLITTLE.py \
--big-cpus=2 \
--little-cpus=2 \
--disk "$(pwd)/data/aarch-system-20170616/disks/linaro-minimal-aarch64.img" \
--kernel "$(pwd)/data/aarch-system-20170616/binaries/vmlinux.vexpress_gem5_v1_64.20170616" \
--caches \
| ts -s
;
....
The first terminal message appears at 4 minutes, and boot finishes at 7 minutes, but then I wait forever and no shell. Looks like it runs a big init, lol?
Trying to boot `aarch64` QEMU with the magic image shows nothing on screen, but it must be a simple output problem, because `trace2lines` says that `start_kernel` and `kernel_init` are reached, but `init=/poweroff.out` does not turn off the machine.
We then extract the kernel config from the image with: https://stackoverflow.com/questions/14958192/how-to-get-the-config-from-a-linux-kernel-image/14958263#14958263
....
./linux/scripts/extract-ikconfig "$(pwd)/data/aarch-system-20170616/binaries/vmlinux.vexpress_gem5_v1_64.20170616"
....
But QEMU works fine if the kernel is compiled with that config, so I am confused, how are the two kernels different? The only missing difference is the kernel version.
We then try to boot gem5 with our kernel built with the extracted config, but no change.
I then checked out to https://gem5.googlesource.com/arm/linux didn't help. And finally when I add `--dtb out/aarch64/buildroot/build/gem5-1.0/gem5/system/arm/dt/armv8_gem5_v1_big_little_2_2.dtb` on top, it started showing boot messages!
`cat /proc/cpuinfo` shows 4 identical CPUs instead of 2 of two differnt types, likely because gem5 does not expose some informational register much like the caches: https://www.mail-archive.com/gem5-users@gem5.org/msg15426.html `config.ini` does show that the two big ones are `DerivO3CPU` and the small ones are `MinorCPU`.
== Insane action

11
fs-biglittle Executable file
View File

@@ -0,0 +1,11 @@
#!/usr/bin/env bash
M5_PATH="$(pwd)/out/aarch64/buildroot/build/gem5-1.0/system" \
./out/aarch64/buildroot/build/gem5-1.0/gem5/build/ARM/gem5.opt \
./out/aarch64/buildroot/build/gem5-1.0/gem5/configs/example/arm/fs_bigLITTLE.py \
--disk="$(pwd)/out/aarch64/buildroot/images/rootfs.ext2" \
--kernel="$(pwd)/out/aarch64/buildroot/build/linux-custom/vmlinux" \
--big-cpus=2 \
--little-cpus=2 \
--caches \
--dtb "$(pwd)/out/aarch64/buildroot/build/gem5-1.0/gem5/system/arm/dt/armv8_gem5_v1_big_little_2_2.dtb" \
;