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TASKLIST.md

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Tasklist for the HAVK operating system and kernel

Last Updated: 2021-05-28

High priority

  • The kernel crashes on AMD systems (but not Intel systems) during some point in which my descriptor tables are prepared and loaded, which points to the idea that they're not completely free of formatting errors. Note that this crash has only been observed on a AMD Ryzen 7 1700X processor.
  • Create a package for better concurrency support e.g. mutexes.
  • Implement user-space signal handling so user tasks can handle interrupts. Currently needed for better PS/2 operability. Either store interrupt data in a kernel structure or clobber the MMX registers and store it there.
  • Start thinking of a way to do memory-mapped I/O for user space drivers, as tasks will need to interact with hardware. PCI(e) enumeration and access may be done inside the kernel.
  • Implement or port over some sort of shell/interpreter. I may create my own scripting language.

Low priority

  • Set the LAPIC timer to one-shot mode whenever a task is switched. This might be better than an interrupt every specific period due to less pointless interruptions.
  • Implement FAT12 and FAT32 support, along with a VFAT driver.
  • Improve the capabilities of the ATA PIO operations, particularly error checking. In regards to tasking, the tasks which depend on the ATA driver task expect no sudden task terminations and cannot reset themselves accordingly.
  • Trampoline the APs so we can use more than one core. I'd like to avoid concurrency issues and performance is not a demand, so leave this out until the tasking system is solid. This includes pointing the GS register's base address to a CPU-specific structure/record which includes tasking information etc.
  • Finally start engaging with security concepts centred around user space. This includes handling x86 IOPBs properly for each task.
  • Rework the physical frame allocator.
  • Make the build system better and more convenient for proving operating system tasks programmed in SPARK.
  • Handle the CPU exceptions which currently aren't handled by the tasking functionality, as they occasionally are raised by tasks due to errors.
  • Come up with a way to make IPC interfaces cleaner from a programming perspective. I have been implementing them on an ad hoc basis.
  • Clean up the entire operating system runtime overall, as I have been rushing it in comparison to the care I have been taking with the kernel.
  • Redo the IPC handling for some of the user tasks that have been ignored due to the now bygone IPC performance issues.
  • Slightly rework the tasking package's contracts, as there are too many dead task checks that raise a panic if reached. This should not actually be necessary if modelled more carefully.
  • Move the PIT driver out of the kernel, as it has no reason to be inside the kernel any more aside from initially calibrating the LAPIC timer.
  • Make IPC more fair and give tasks more control over context switching, along with what tasks are actually active so an expensive system call does not have to be used in order for every task in order to check if they've received a message. This can also potentially lead to taking the scheduler out of the kernel; thus, further pushing it towards a microkernel.