48 lines
2.5 KiB
Markdown
48 lines
2.5 KiB
Markdown
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---
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title: "page_frame.h"
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summary: "physical memory management"
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---
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# `PFRAME_SIZE` - macro
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The size of one page (4KB).
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# `page_frame_manager_T` - struct
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| Name | Type | Description |
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|-------------------|----------|------------------------------------------------------------------------------------|
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| free_memory | uint64_t | The amount of free/usable memory in bytes |
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| reserved_memory | uint64_t | The amount of reserved memory in bytes |
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| used_memory | uint64_t | The amount of memory used by noxos in bytes |
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| page_bitmap_index | uint64_t | The index to the first free page |
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| page_bitmap | bitmap_T | A huge bitmap, that stores, which pages are claimable and which are already in use |
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| blocked | bool | Thread safety guard |
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#### `pframe_manager_init()` - function (void)
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Initializes the page frame manager, needs to be called once at kernel init.
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#### `pframe_reserve(address)` - function (void) [Thread Safe]
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Blocks a page, so it can't be requested or anything else.
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If the page is already blocked by anything else, e.g. by a request, it won't be reserved.
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#### `pframe_reserve_multi(address, n)` - function (void) [Thread Safe]
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Reserves the page at the given address, plus *n* pages after that page.
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#### `pframe_unreserve(address)` - function (void) [Thread Safe]
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Unreserves a reserved page and makes it accessible again.
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#### `pframe_unreserve_multi(address, n)` - function (void) [Thread Safe]
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Unreserves the page at the given address, plus *n* pages after that page.
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#### `pframe_request()` - function (void*) [Thread Safe]
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Returns the physical address of a page.
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This is kind of the low level version of `memory_allocate`.
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#### `pframe_free(address)` - function (void) [Thread Safe]
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Needs a valid page address produced by [pframe_request](https://nerdcult.net/projects/noxos/docs/codebase/mm/page_frame.h/#pframe_request---function-void-thread-safe) as argument.
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Invalidates the address and frees it, so it can be requested again.
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This is kind of the low level version of `memory_free`.
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#### `pframe_free_multi(address, n)` - function (void) [Thread Safe]
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Frees the page at the given address, plus *n* pages after that page.
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