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Now that the other CPUs have been brought up, add support for scheduling tasks on them. The scheduler now maintains separate ready/blocked lists per CPU, and CPUs will attempt to balance load via periodic work stealing. Other changes as a result of this: - The device manager no longer creates a local APIC object, but instead just gathers relevant info from the APCI tables. Each CPU creates its own local APIC object. This also spurred the APIC timer calibration to become a static value, as all APICs are assumed to be symmetrical. - Fixed a bug where the scheduler was popping the current task off of its ready list, however the current task is never on the ready list (except the idle task was first set up as both current and ready). This was causing the lists to get into bad states. Now a task can only ever be current or in a ready or blocked list. - Got rid of the unused static process::s_processes list of all processes, instead of trying to synchronize it via locks. - Added spinlocks for synchronization to the scheduler and logger objects.
jsix: A hobby operating system
jsix is the hobby operating system that I am currently building. It's far from finished, or even being usable. Instead, it's a sandbox for me to play with kernel-level code and explore architectures.
The design goals of the project are:
-
Modernity - I'm not interested in designing for legacy systems, or running on all hardware out there. My target is only 64 bit architecutres, and modern commodity hardware. Currently that means x64 systems with Nehalem or newer CPUs and UEFI firmware. (See this list for the currently required CPU features.) Eventually I'd like to work on an AArch64 port, partly to force myself to factor out the architecture-dependent pieces of the code base.
-
Modularity - I'd like to pull as much of the system out into separate processes as possible, in the microkernel fashion. A sub-goal of this is to explore where the bottlenecks of such a microkernel are now, and whether eschewing legacy hardware will let me design a system that's less bogged down by the traditional microkernel problems.
-
Exploration - I'm really mostly doing this to have fun learning and exploring modern OS development. Modular design may be tossed out (hopefully temporarily) in some places to allow me to play around with the related hardware.
A note on the name: This kernel was originally named Popcorn, but I have since
discovered that the Popcorn Linux project is also developing a kernel with that
name, started around the same time as this project. So I've renamed this kernel
jsix (Always styled jsix or j6, never capitalized) as an homage to L4, xv6,
and my wonderful wife.
Building
jsix uses the Ninja build tool, and generates the build files for it with a custom tool called Bonnibel. Bonnibel can be installed with Cargo, or downloaded as a prebuilt binary from its Github repository.
Requrirements:
- bonnibel
- ninja
- clang
- nasm
- mtools
- curl for downloading the toolchain
Setting up the cross toolchain
Running pb sync will download and unpack the toolchain into sysroot.
Compiling the toolchain yourself
If you have clang and curl installed, runing the scripts/build_sysroot.sh
script will download and build a LLVM toolchain configured for building jsix
host binaries.
Building and running jsix
Once the toolchain has been set up, running Bonnibel's pb init command will
set up the build configuration, and pb build will actually run the build. If
you have qemu-system-x86_64 installed, the qemu.sh script will to run jsix
in QEMU -nographic mode.
I personally run this either from a real debian amd64 testing/buster machine or a windows WSL debian testing/buster installation. The following should be enough to set up such a system to build the kernel:
sudo apt install qemu-system-x86 nasm clang-10 mtools curl ninja-build
sudo update-alternatives /usr/bin/clang clang /usr/bin/clang-10 1000
sudo update-alternatives /usr/bin/clang++ clang++ /usr/bin/clang++-10 1000
curl -L -o pb https://github.com/justinian/bonnibel_rs/releases/download/v2.3.0/pb-linux-amd64 && chmod a+x pb