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

organize sections a bit, gem5 link time more info

Browse Source
This commit is contained in:
Ciro Santilli 六四事件 法轮功
2020-09-25 02:00:01 +00:00
parent 5562474994
commit b3401b61ed
1 changed files with 88 additions and 51 deletions
Download Patch File Download Diff File Expand all files Collapse all files

139
README.adoc
View File

@@ -5638,8 +5638,20 @@ If you don't want to start the NFS server after the next boot automatically so s
systemctl disable nfs-kernel-server
....
== Operating systems
https://en.wikipedia.org/wiki/Operating_system
* <<linux-kernel>>
* <<freebsd>>
* <<rtos>>
* <<xen>>
* <<u-boot>>
== Linux kernel
https://en.wikipedia.org/wiki/Linux_kernel
=== Linux kernel configuration
==== Modify kernel config
@@ -9856,8 +9868,62 @@ See also:
* https://stackoverflow.com/questions/5429137/how-to-print-register-values-in-gdb/31340294#31340294
* https://stackoverflow.com/questions/24169614/how-to-show-all-x86-control-registers-when-debugging-the-linux-kernel-in-gdb-thr/59311764#59311764
== FreeBSD
https://en.wikipedia.org/wiki/FreeBSD
Prebuilt on Ubuntu 20.04 worked: https://stackoverflow.com/questions/49656395/how-to-boot-freebsd-image-under-qemu/64027161#64027161[]
TODO minimal build + boot on QEMU example anywhere???
== RTOS
https://en.wikipedia.org/wiki/Real-time_operating_system
=== Zephyr
https://en.wikipedia.org/wiki/Zephyr_(operating_system)
Zephyr is an RTOS that has <<posix>> support. I think it works much like our <<baremetal-setup>> which uses Newlib and generates individual ELF files that contain both our C program's code, and the Zephyr libraries.
TODO get a hello world working, and then consider further integration in this repo, e.g. being able to run all C userland content on it.
TODO: Cortex-A CPUs are not currently supported, there are some `qemu_cortex_m0` boards, but can't find a QEMU Cortex-A. There is an x86_64 qemu board, but we don't currently have an <<about-the-baremetal-setup,x86 baremetal toolchain>>. For this reason, we won't touch this further for now.
However, unlike Newlib, Zephyr must be setting up a simple pre-main runtime to be able to handle threads.
Failed attempt:
....
# https://askubuntu.com/questions/952429/is-there-a-good-ppa-for-cmake-backports
wget -O - https://apt.kitware.com/keys/kitware-archive-latest.asc 2>/dev/null | sudo apt-key add -
sudo apt-add-repository 'deb https://apt.kitware.com/ubuntu/ bionic-rc main'
sudo apt-get update
sudo apt-get install cmake
git clone https://github.com/zephyrproject-rtos/zephyr
pip3 install --user -U west packaging
cd zephyr
git checkout v1.14.1
west init zephyrproject
west update
export ZEPHYR_TOOLCHAIN_VARIANT=xtools
export XTOOLS_TOOLCHAIN_PATH="$(pwd)/out/crosstool-ng/build/default/install/aarch64/bin/"
source zephyr-env.sh
west build -b qemu_aarch64 samples/hello_world
....
The build system of that project is a bit excessive / wonky. You need an edge CMake not present in Ubuntu 18.04, which I don't want to install right now, and it uses the weird custom `west` build tool frontend.
=== ARM Mbed
https://en.wikipedia.org/wiki/Mbed
TODO minimal setup to run it on QEMU? Possible?
== Xen
https://en.wikipedia.org/wiki/Xen
TODO: get prototype working and then properly integrate:
....
@@ -9913,6 +9979,14 @@ U-Boot is a popular bootloader.
It can read disk filesystems, and Buildroot supports it, so we could in theory put it into memory, and let it find a kernel image from the root filesystem and boot that, but I didn't manage to get it working yet: https://stackoverflow.com/questions/58028789/how-to-boot-linux-aarch64-with-u-boot-with-buildroot-on-qemu
== Emulators
https://en.wikipedia.org/wiki/Emulator
* <<qemu>>
* <<gem5>>
* <<gensim>>
== QEMU
=== Introduction to QEMU
@@ -27189,15 +27263,26 @@ Some approximate reference values on <<p51>>:
* `opt`
** unmodified: 10 seconds
** hack with `-fuse-ld=gold`: 6 seconds. Huge improvement!
** `LDFLAGS_EXTRA=-fuse-ld=gold`: 6 seconds. Huge improvement! Note that in general you have to do a full rebuild or else link may fail: https://sourceware.org/bugzilla/show_bug.cgi?id=23869
+
More info on gold:
+
*** https://stackoverflow.com/questions/3476093/replacing-ld-with-gold-any-experience/53921263#53921263
*** https://gem5-review.googlesource.com/c/public/gem5/+/14075
* `debug`
** unmodified: 14 seconds. Why two times slower than unmodified?
** hack with `-fuse-ld=gold`: `internal error in read_cie, at ../../gold/ehframe.cc:919` on Ubuntu 18.04 all GCC. TODO report.
** unmodified: 14 seconds. Why so much slower than unmodified?
** `-fuse-ld=gold`: `internal error in read_cie, at ../../gold/ehframe.cc:919` on Ubuntu 18.04 all GCC. https://sourceware.org/bugzilla/show_bug.cgi?id=23869
* `fast`
** `--force-lto`: 1 minute. Slower as expected, since more optimizations are done at link time. `--force-lto` is only used for `fast`, and it adds `-flto` to the build.
* `opt LDFLAGS_EXTRA=-s`: stripping the executable greatly reduces link time, but you get no symbols
ramfs made no difference, the kernel must be caching files in memory very efficiently already.
In addition to the link time, scons startup time can also be considerable:
* https://gem5.atlassian.net/browse/GEM5-256
* https://gem5-review.googlesource.com/c/public/gem5/+/25385
Tested at: d4b3e064adeeace3c3e7d106801f95c14637c12f + 1.
=== Benchmark machines
@@ -27435,54 +27520,6 @@ gem5:
** https://stackoverflow.com/questions/47997565/gem5-system-requirements-for-decent-performance/48941793#48941793
** https://github.com/gem5/gem5/issues/25
== FreeBSD
Prebuilt on Ubuntu 20.04 worked: https://stackoverflow.com/questions/49656395/how-to-boot-freebsd-image-under-qemu/64027161#64027161[]
TODO minimal build + boot on QEMU example anywhere???
== RTOS
=== Zephyr
https://en.wikipedia.org/wiki/Zephyr_(operating_system)
Zephyr is an RTOS that has <<posix>> support. I think it works much like our <<baremetal-setup>> which uses Newlib and generates individual ELF files that contain both our C program's code, and the Zephyr libraries.
TODO get a hello world working, and then consider further integration in this repo, e.g. being able to run all C userland content on it.
TODO: Cortex-A CPUs are not currently supported, there are some `qemu_cortex_m0` boards, but can't find a QEMU Cortex-A. There is an x86_64 qemu board, but we don't currently have an <<about-the-baremetal-setup,x86 baremetal toolchain>>. For this reason, we won't touch this further for now.
However, unlike Newlib, Zephyr must be setting up a simple pre-main runtime to be able to handle threads.
Failed attempt:
....
# https://askubuntu.com/questions/952429/is-there-a-good-ppa-for-cmake-backports
wget -O - https://apt.kitware.com/keys/kitware-archive-latest.asc 2>/dev/null | sudo apt-key add -
sudo apt-add-repository 'deb https://apt.kitware.com/ubuntu/ bionic-rc main'
sudo apt-get update
sudo apt-get install cmake
git clone https://github.com/zephyrproject-rtos/zephyr
pip3 install --user -U west packaging
cd zephyr
git checkout v1.14.1
west init zephyrproject
west update
export ZEPHYR_TOOLCHAIN_VARIANT=xtools
export XTOOLS_TOOLCHAIN_PATH="$(pwd)/out/crosstool-ng/build/default/install/aarch64/bin/"
source zephyr-env.sh
west build -b qemu_aarch64 samples/hello_world
....
The build system of that project is a bit excessive / wonky. You need an edge CMake not present in Ubuntu 18.04, which I don't want to install right now, and it uses the weird custom `west` build tool frontend.
=== ARM Mbed
https://en.wikipedia.org/wiki/Mbed
TODO minimal setup to run it on QEMU? Possible?
== Compilers
Argh, compilers are boring, let's learn a bit about them.