121 lines
4.4 KiB
C
Executable file
121 lines
4.4 KiB
C
Executable file
/* Entry points into this file:
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* mem_init: create a list a free memory
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* alloc_segments: allocate segments for 8088 or higher processor
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*/
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#include "kernel.h"
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#include "protect.h"
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#include "proc.h"
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#if (CHIP == INTEL)
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/* In real mode only 1M can be addressed, and in 16-bit protected we can go
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* no further than we can count in clicks. (The 286 is further limited by
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* its 24 bit address bus, but we can assume in that case that no more than
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* 16M memory is reported by the BIOS.)
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*/
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#define MAX_REAL 0x00100000L
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#define MAX_16BIT (0xFFF0L << CLICK_SHIFT)
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/*=========================================================================*
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* mem_init *
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*=========================================================================*/
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PUBLIC void mem_init()
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{
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/* Initialize the free memory list from the 'memory' boot variable. Translate
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* the byte offsets and sizes in this list to clicks, properly truncated. Also
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* make sure that we don't exceed the maximum address space of the 286 or the
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* 8086, i.e. when running in 16-bit protected mode or real mode.
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*/
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long base, size, limit;
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char *s, *end; /* use to parse boot variable */
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int i;
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struct memory *memp;
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#if _WORD_SIZE == 2
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unsigned long max_address;
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#endif
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/* The available memory is determined by MINIX' boot loader as a list of
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* (base:size)-pairs in boothead.s. The 'memory' boot variable is set in
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* in boot.s. The format is "b0:s0,b1:s1,b2:s2", where b0:s0 is low mem,
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* b1:s1 is mem between 1M and 16M, b2:s2 is mem above 16M. Pairs b1:s1
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* and b2:s2 are combined if the memory is adjacent.
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*/
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s = getkenv("memory"); /* get memory boot variable */
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tot_mem_size = 0;
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for (i = 0; i < NR_MEMS; i++) {
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memp = &mem[i]; /* result is stored here */
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base = size = 0;
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if (*s != 0) { /* end of boot variable */
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/* Expect base to be read (end != s) and ':' as next char. */
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base = kstrtoul(s, &end, 0x10); /* get number */
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if (end != s && *end == ':') s = ++end; /* skip ':' */
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else *s=0; /* fake end for next; should not happen */
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/* Expect size to be read and skip ',', unless at end. */
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size = kstrtoul(s, &end, 0x10); /* get number */
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if (end != s && *end == ',') s = ++end; /* skip ',' */
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else if (end != s && *end == 0) s = end; /* end found */
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else *s=0; /* fake end for next; should not happen */
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}
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limit = base + size;
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#if _WORD_SIZE == 2
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max_address = protected_mode ? MAX_16BIT : MAX_REAL;
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if (limit > max_address) limit = max_address;
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#endif
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base = (base + CLICK_SIZE-1) & ~(long)(CLICK_SIZE-1);
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limit &= ~(long)(CLICK_SIZE-1);
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if (limit <= base) continue;
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memp->base = base >> CLICK_SHIFT;
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memp->size = (limit - base) >> CLICK_SHIFT;
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tot_mem_size += memp->size;
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}
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}
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/*==========================================================================*
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* alloc_segments *
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*==========================================================================*/
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PUBLIC void alloc_segments(rp)
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register struct proc *rp;
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{
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/* This is called at system initialization from main() and by do_newmap().
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* The code has a separate function because of all hardware-dependencies.
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* Note that IDLE is part of the kernel and gets TASK_PRIVILEGE here.
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*/
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phys_bytes code_bytes;
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phys_bytes data_bytes;
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int privilege;
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if (protected_mode) {
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data_bytes = (phys_bytes) (rp->p_memmap[S].mem_vir +
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rp->p_memmap[S].mem_len) << CLICK_SHIFT;
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if (rp->p_memmap[T].mem_len == 0)
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code_bytes = data_bytes; /* common I&D, poor protect */
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else
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code_bytes = (phys_bytes) rp->p_memmap[T].mem_len << CLICK_SHIFT;
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privilege = (isidlep(rp) || istaskp(rp)) ?
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TASK_PRIVILEGE : USER_PRIVILEGE;
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init_codeseg(&rp->p_ldt[CS_LDT_INDEX],
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(phys_bytes) rp->p_memmap[T].mem_phys << CLICK_SHIFT,
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code_bytes, privilege);
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init_dataseg(&rp->p_ldt[DS_LDT_INDEX],
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(phys_bytes) rp->p_memmap[D].mem_phys << CLICK_SHIFT,
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data_bytes, privilege);
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rp->p_reg.cs = (CS_LDT_INDEX * DESC_SIZE) | TI | privilege;
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#if _WORD_SIZE == 4
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rp->p_reg.gs =
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rp->p_reg.fs =
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#endif
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rp->p_reg.ss =
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rp->p_reg.es =
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rp->p_reg.ds = (DS_LDT_INDEX*DESC_SIZE) | TI | privilege;
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} else {
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rp->p_reg.cs = click_to_hclick(rp->p_memmap[T].mem_phys);
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rp->p_reg.ss =
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rp->p_reg.es =
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rp->p_reg.ds = click_to_hclick(rp->p_memmap[D].mem_phys);
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}
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}
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#endif /* (CHIP == INTEL) */
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