noxos (docs): merged 'platform' docs from .wiki
This commit is contained in:
parent
3e4fadbeb4
commit
f06b61486d
|
|
@ -0,0 +1,46 @@
|
|||
---
|
||||
title: "cpu.h"
|
||||
summary: "stuff related directly with the cpu"
|
||||
---
|
||||
|
||||
OSDev Wiki: [x86 CPU Registers](https://wiki.osdev.org/CPU_Registers_x86)
|
||||
|
||||
# `cpu_state_T` - struct
|
||||
- **cr3** - Control register 3, holds the current page table
|
||||
- **rax** - General purpose register
|
||||
- **rbx** - General purpose register
|
||||
- **rcx** - General purpose register
|
||||
- **rdx** - General purpose register
|
||||
- **rsi** - General purpose register
|
||||
- **rdi** - General purpose register
|
||||
- **rbp** - The Bottom of the current stack frame
|
||||
- **interrupt_id** - The ID of the interrupt, that captured the cpu state
|
||||
- **error_code** - Some exceptions such as the Page fault push more detailed information into here
|
||||
- **rip** - The current instruction address
|
||||
- **cs** - Segment selector of the associated IDT descriptor
|
||||
- **flags** - The CPU's FLAGS register, a status bitmap -> [cpu_flags_E](https://nerdcult.net/projects/noxos/docs/codebase/platform/cpu.h/#cpu_flags_e---enum)
|
||||
- **rsp** - The Top of the current stack frame
|
||||
- **ss** - Not totally sure, what this does, but it has to do with security rings
|
||||
|
||||
This struct defines a *complete* CPU state, that can be saved and restored.
|
||||
Such a state is saved when the CPU fires an interrupt and restored by the interrupt handler when it's finished.
|
||||
This allows multithreading and exception analysis.
|
||||
# `cpu_flags_E` - enum
|
||||
- **CPU_FLAG_CARRY**
|
||||
- **CPU_FLAG_PARITY**
|
||||
- **CPU_FLAG_AUXILIARY**
|
||||
- **CPU_FLAG_ZERO**
|
||||
- **CPU_FLAG_SIGN**
|
||||
- **CPU_FLAG_TRAP**
|
||||
- **CPU_FLAG_INTERRUPT_ENABLE**
|
||||
- **CPU_FLAG_DIRECTION**
|
||||
- **CPU_FLAG_OVERFLOW**
|
||||
- **CPU_FLAG_IO_PRIVILEGE_0**
|
||||
- **CPU_FLAG_IO_PRIVILEGE_1**
|
||||
- **CPU_FLAG_NESTED_TASK**
|
||||
- **CPU_FLAG_RESUME**
|
||||
- **CPU_FLAG_VIRTUAL_8086**
|
||||
- **CPU_FLAG_ALIGNMENT_CHECK**
|
||||
- **CPU_FLAG_VIRTUAL_INTERRUPT**
|
||||
- **CPU_FLAG_VIRTUAL_INTERRUPT_PENDING**
|
||||
- **CPU_FLAG_CPUID**
|
||||
|
|
@ -0,0 +1,16 @@
|
|||
---
|
||||
title: "exceptions.h"
|
||||
summary: "CPU-exception handling"
|
||||
---
|
||||
|
||||
OSDev Wiki: [Exceptions](https://wiki.osdev.org/Exceptions)
|
||||
|
||||
# `exception_type_E` - enum
|
||||
These are just the definitions of the CPU-exception interrupt IDs.
|
||||
|
||||
# `g_exception_type_strings` - global variable
|
||||
This array of strings defines the names of the CPU-exceptions.
|
||||
|
||||
# `exception_handle(cpu_state)` - function (cpu_state_T*)
|
||||
If an interrupt is an exception, the interrupt handler will call this function to handle the exception.
|
||||
At the moment it will just panic, but in far future this could get expanded for page swapping, etc.
|
||||
|
|
@ -0,0 +1,51 @@
|
|||
---
|
||||
title: "gdt.h"
|
||||
summary: "definitions to handle segments (_Global Descriptor Table_)"
|
||||
---
|
||||
|
||||
Segmentation is deprecated and is only needed for backwards compatibility.
|
||||
|
||||
OSDev Wiki: [Global Descriptor Table](https://wiki.osdev.org/GDT)
|
||||
|
||||
# `gdt_selector_E` - enum
|
||||
- **Null**
|
||||
- **Kernel Code** - Readable
|
||||
- **Kernel Data** - Readable + Writable
|
||||
- **User Null**
|
||||
- **User Code** - Readable
|
||||
- **User Data** - Readable + Writable
|
||||
|
||||
# `gdt_descriptor_T` - struct [packed]
|
||||
|
||||
| Name | Type | Description |
|
||||
|--------|----------|-----------------------------------------------------|
|
||||
| size | uint16_t | The tables size in bytes (-1) |
|
||||
| offset | uint64_t | The virtual address, where the table lies in memory |
|
||||
|
||||
|
||||
# `gdt_entry_T` - struct [packed]
|
||||
| Name | Type | Description |
|
||||
|--------------|----------|--------------------------------------------------------------|
|
||||
| limit0 | uint16_t | Can be ignored in long mode |
|
||||
| base0 | uint16_t | Can be ignored in long mode |
|
||||
| base1 | uint8_t | Can be ignored in long mode |
|
||||
| access | uint8_t | Specifies permissions (details in osdev wiki) |
|
||||
| limit1_flags | uint8_t | The first 4 bits can be ignored and the last 4 specify flags |
|
||||
| base2 | uint8_t | Can be ignored in long mode |
|
||||
|
||||
# `gdt_T` - struct [packed / page aligned]
|
||||
| Name | Type | Description |
|
||||
|-------------|-------------|------------------------------------------|
|
||||
| null | gdt_entry_T | The entry for `GDT_SELECTOR_NULL` |
|
||||
| kernel_code | gdt_entry_T | The entry for `GDT_SELECTOR_KERNEL_CODE` |
|
||||
| kernel_data | gdt_entry_T | The entry for `GDT_SELECTOR_KERNEL_DATA` |
|
||||
| user_null | gdt_entry_T | The entry for `GDT_SELECTOR_USER_NULL` |
|
||||
| user_code | gdt_entry_T | The entry for `GDT_SELECTOR_USER_CODE` |
|
||||
| user_data | gdt_entry_T | The entry for `GDT_SELECTOR_USER_DATA` |
|
||||
|
||||
# `g_default_gdt` - global variable
|
||||
The systems GDT.
|
||||
|
||||
# `gdt_init` - function (void)
|
||||
Populates and loads [g_default_gdt](https://nerdcult.net/projects/noxos/docs/codebase/platform/gdt.h/#g_default_gdt---global-variable).
|
||||
This will also set all the data segment registers to 0x10 (Kernel Data) and `cs` to 0x08 (Kernel Code).
|
||||
|
|
@ -0,0 +1,22 @@
|
|||
---
|
||||
title: "interrupts.h"
|
||||
summary: "the infrastructure to handle x86 interrupts"
|
||||
---
|
||||
|
||||
# `idt_register_T` - struct [packed]
|
||||
This struct is very similar to the [GDT descriptor](https://nerdcult.net/projects/noxos/docs/codebase/platform/gdt.h/#gdt_descriptor_t---struct-packed).
|
||||
It holds the size and address of the Table, where the interrupt handlers are looked up.
|
||||
|
||||
# `idt_descriptor_entry_T` - struct
|
||||
This struct stores information about one interrupt handler.
|
||||
The osdev wiki explains this more detailed.
|
||||
|
||||
# `g_idt_register` - global variable
|
||||
The default IDT configuration loaded when the IDT gets initialized.
|
||||
|
||||
# `g_handling_interrupt` - global variable
|
||||
When the system isn't handling an interrupt this is set to 0.
|
||||
If this is greater than 0 the system is currently handling an interrupt,
|
||||
|
||||
# `idt_init()` - function (void)
|
||||
This function fills all the interrupt gates (handlers) into the IDT and loads it.
|
||||
Reference in New Issue