ChengCheng OS (CCOS) is a hobby 64 bit operating system. I'm writing it on x86, because I like sadness and misery. This project was still in developing. I'm a beginner for operating system design. Many of the design concepts I have implemented are inspired by Windows NT such as ccldr (OS Loader for ChengCheng OS) and Memory manager. And, there is plenty more courses that I need to learn in the comming months. So, I will not update the project frequently.
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UEFI
CCOS uses UEFI to bootstrap ccoskrnl. UEFI greatly facilitates OS Loader developing. Developer can directly call the interfaces provided by UEFI (Use C language instead of assembly). There is one thing to note here, that CCOS still needs ccldr (another binary executable file) to load ccoskrnl. It is a bit like "a second stage boot loader". But in fact, BOOTX64.efi just simply divides kernel space and searches for a suitable physical memory space for ccoskrnl image loading. Then ccldr will map kernel space into high address of virtual address space and set GDT(Global Descriptor Table, a significant structure for x86 architecture.)
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Multi-Cores
Multi-cores support is an enormous challenge for me. I do not guarantee a good implementation of multi-cores system. For now, CCOS can correctly active other application cores. Not like other operating system demo, CCOS puts application cores initialization routine at a isolated binary file and load it into the first 1 MiB of physical memory and construct separately the page table for the memory space. Before of application cores running, CCOS will fix the citation of relative address of the binary program. I have to admit, this is a foolish design.
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APIC
APIC(Advanced Programmable Interrupt Controller) is a critical component in modern computer system. It provides the possibility for multi-cores system and supports multilevel interrupt priority on the hardware level. Unfortunately, APIC is complicated. Since to fully understand APIC needs sound knowledge of computer system, I only implement the basic driver of APIC.
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TrueType
CCOS displays characters on screen through rendering TrueType Fonts(Default font in CCOS is Adobe Source Han Sans SC VF). It's not worth to output characters using TrueType rendering. For early OS developing, using bitmap font is more recommended method of characters output.
These is a cirtical issus here, which is that the preformence of text output of CCOS is very pool. The badly performing will seriously slow down the running of ccos. I don't know how to optimize the function because the font drawing is a relatively complex process. Another method is use bitmap font to instead the TrueType font.
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Wide Char
CCOS offers two character type, "char" and "wch_t"(wide char, 4-bytes), for storing all characters. Regardless of the character type, CCOS always converts wch_t first, then outputs a wide string. In fact, TrueType parser in CCOS only uses "Unicode 2.0 and onwards semantics", which platform ID = 0 and Encoding ID = 3 in cmap(cmap — Character to Glyph Index Mapping Table, a struture in TrueType.). Therefore, it exclusively supports Unicode Basic Multilingual Plane characters (U+0000 to U+FFFF).
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Memory Manager
The design ideas of memory management is inspired by Window NT, which contains PFN database, Lookside, Page-Directory self mapping scheme, lamination memory pool management and so on, but not all.
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Graphics Output with multi-windows
CCOS supports multi-windows, which means it can output text in different window on screen. It's uesful to debug multi-cores through open a text-output window to each core. Even if not have mouse driver, user also can use keyboard to select which window need to enter characters.
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Bug fix: Add spinlock to prevent conflicts of multiple windows output
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Dynamic memory manager with memory leaks detection
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System PTE management
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PCIe management
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NVMe Driver
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Keyboard Driver (Not urgent)
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Use bitmap fonts rather than TypeTrue Fonts rendering.
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Power Management.
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CPU prefromence management.
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QEMU with 2 GiB RAM or higher
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x86_64 CPU (Intel or AMD) with AVX instruction set
For installation, please refer to the ccoskrnl build
The math library(reflibs/libm.a) was provided by @Estrella
No license.
E-mail: 2010705797@qq.com
ChengCheng OS: https://github.com/ccoskrnl/ccoskrnl