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[project] README updates

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Justin C. Miller
2022-02-28 21:48:18 -08:00
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# The jsix operating system # The jsix operating system
**jsix** is a custom multi-core x64 operating system that I am building from **jsix** is a custom multi-core x64 operating system that I am building from
scratch. It's far from finished, or even being usable - see the *Status and scratch. It's far from finished, or even being usable (see the *Status and
Roadmap* section, below. Roadmap* section, below) but all currently-planned major kernel features are
now implemented to at least a passable level.
The design goals of the project are: The design goals of the project are:
@@ -77,34 +78,36 @@ per core. Cores periodically attempt to balance load via work stealing.
User-space tasks are able to create threads as well as other processes. User-space tasks are able to create threads as well as other processes.
Several kernel-only tasks exist, though I'm trying to reduce that. Eventually
only the timekeeping task should be a separate kernel-only thread.
#### API #### API
_In progress._ User-space tasks are able to make syscalls to the kernel via _Syscalls: Sufficient._ User-space tasks are able to make syscalls to the
fast SYSCALL/SYSRET instructions. Syscalls made via `libj6` look to both the kernel via fast SYSCALL/SYSRET instructions. Syscalls made via `libj6` look to
callee and the caller like standard SysV ABI function calls. The both the callee and the caller like standard SysV ABI function calls. The
implementations are wrapped in generated wrapper functions which validate the implementations are wrapped in generated wrapper functions which validate the
request, check capabilities, and find the appropriate kernel objects or handles request, check capabilities, and find the appropriate kernel objects or handles
before calling the implementation functions. before calling the implementation functions.
Current work in this area: _IPC: Working, needs optimization._ The current IPC primitives are:
- The protocol for processes and their children for both initialization and - _Mailboxes_: endpoints for asynchronously-delivered small messages. Currently
sharing resources. The kernel is ignorant of this, except for providing IPC these messages are double-copied - once from the caller into a kernel buffer,
capabilities. and once from the kernel to the receiver. This works and is not a major cause
of slowdown, but will need to be optimized in the future.
- _Channels_: endpoints for asynchronous uni-directional streams of bytes.
Currently these also suffer from a double-copy problem, and should probably
be replaced eventually by userspace shared memory communication.
- _Events_: objects that can be signalled to send asynchronous notifications to
waiting threads.
#### Hardware Support #### Hardware Support
* Framebuffer driver: _In progress._ Currently on machines with a video - Framebuffer driver: _In progress._ Currently on machines with a video
device accessible by UEFI, jsix starts a user-space framebuffer driver that device accessible by UEFI, jsix starts a user-space framebuffer driver that
only prints out kernel logs. only prints out kernel logs.
* Serial driver: _In progress._ The current UART driver does not expose the - Serial driver: _In progress._ The current UART currently only exposes COM1
UART as an output resource yet, it merely gets the kernel logs and sends as an output channel, but no input or other serial ports are exposed.
them over serial. - USB driver: _To do_
* USB driver: _To do_ - AHCI (SATA) driver: _To do_
* AHCI (SATA) driver: _To do_
## Building ## Building