46 lines
1.3 KiB
C
Executable File
46 lines
1.3 KiB
C
Executable File
/*
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* <memlayout.h> - Memory layout for Fenix
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* Largely based off memlayout.h from Xv6.
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*/
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#ifndef _MEMLAYOUT
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#define _MEMLAYOUT
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/*
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* For future reference on how memory works.
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* Extended memory starts at 0x100000 (1 MB).
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* It runs from there to some space below the
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* end of the actual physical memory. Here,
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* that space is defined at 0xE000000 (~224 MB).
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* 32-bit devices fill in from the end of
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* physical memory down, starting here at like
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* 256 MB and filling down to the top of
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* our available memory.
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*/
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/* TODO: Maybe we want more than 256 MB available? */
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/*
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Counterpoint: This system isn't designed to use
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a lot of RAM, and it designed to be like a system
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of yore. 256 MB may be too much.
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-Kat
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*/
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#define EXTMEM 0x100000 /* Extended memory start */
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#define PHYSTOP 0xE000000 /* Top of physical memory */
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#define DEVSPACE 0xFE000000 /* 32-bit devices */
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/* Important address space layout stuff */
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#define KERNBASE 0x80000000 /* First kernel virtual address */
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#define KERNLINK (KERNBASE+EXTMEM) /* Kernel link address */
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/* Translations between physical and virtual memory */
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#define V2P(a) (((uint) (a)) - KERNBASE)
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#define P2V(a) ((void *)(((char *) (a)) + KERNBASE))
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/* The above without casts (NC -> No Cast) */
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#define V2P_NC(a) ((a) - KERNBASE)
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#define P2V_NC(a) ((a) + KERNBASE)
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#endif
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