0e2a7a9730
Reduced kernel size by 512KB by moving private buffer into cstart() function. Replaced assertions with erroneous return values. Removed assertions relating to isuserp(rp), since all processes should become user processes; system processes are now treated similar to other processes.
182 lines
6.6 KiB
C
Executable file
182 lines
6.6 KiB
C
Executable file
/* This file contains the C startup code for Minix on Intel processors.
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* It cooperates with mpx.s to set up a good environment for main().
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*
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* This code runs in real mode for a 16 bit kernel and may have to switch
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* to protected mode for a 286.
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* For a 32 bit kernel this already runs in protected mode, but the selectors
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* are still those given by the BIOS with interrupts disabled, so the
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* descriptors need to be reloaded and interrupt descriptors made.
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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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FORWARD _PROTOTYPE( void mem_init, (_CONST char *params));
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FORWARD _PROTOTYPE( char *get_value, (_CONST char *params, _CONST char *key));
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/*==========================================================================*
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* cstart *
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*==========================================================================*/
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PUBLIC void cstart(cs, ds, mds, parmoff, parmsize)
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U16_t cs, ds; /* kernel code and data segment */
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U16_t mds; /* monitor data segment */
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U16_t parmoff, parmsize; /* boot parameters offset and length */
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{
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/* Perform system initializations prior to calling main(). Most settings are
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* determined with help of the environment strings passed by MINIX' loader.
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*/
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char params[128*sizeof(char *)]; /* boot monitor parameters */
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register char *value; /* value in key=value pair */
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unsigned mon_start;
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extern int etext, end;
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/* Decide if mode is protected; 386 or higher implies protected mode.
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* This must be done first, because it is needed for, e.g., seg2phys().
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* For 286 machines we cannot decide on protected mode, yet. This is
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* done below.
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*/
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#if _WORD_SIZE != 2
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machine.protected = 1;
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#endif
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/* Record where the kernel and the monitor are. */
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kinfo.code_base = seg2phys(cs);
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kinfo.code_size = (phys_bytes) &etext; /* size of code segment */
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kinfo.data_base = seg2phys(ds);
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kinfo.data_size = (phys_bytes) &end; /* size of data segment */
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/* Initialize protected mode descriptors. */
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prot_init();
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/* Copy the boot parameters to kernel memory. */
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kinfo.params_base = seg2phys(mds) + parmoff;
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kinfo.params_size = MAX(parmsize,sizeof(params)-2);
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phys_copy(kinfo.params_base, vir2phys(params), kinfo.params_size);
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/* Record miscellaneous information for user-space servers. */
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kinfo.nr_procs = NR_PROCS;
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kinfo.nr_tasks = NR_TASKS;
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kstrncpy(kinfo.version, OS_RELEASE "." OS_VERSION, 6);
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kinfo.proc_addr = (vir_bytes) proc;
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kinfo.kmem_base = vir2phys(0);
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kinfo.kmem_size = (phys_bytes) &end;
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/* Processor? 86, 186, 286, 386, ... */
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machine.processor=katoi(get_value(params, "processor"));
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/* Decide if mode is protected for older machines. */
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#if _WORD_SIZE == 2
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machine.protected = machine.processor >= 286;
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#endif
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if (! machine.protected) mon_return = 0;
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/* XT, AT or MCA bus? */
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value = get_value(params, "bus");
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if (value == NIL_PTR || kstrcmp(value, "at") == 0) {
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machine.pc_at = TRUE; /* PC-AT compatible hardware */
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} else if (kstrcmp(value, "mca") == 0) {
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machine.pc_at = machine.ps_mca = TRUE; /* PS/2 with micro channel */
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}
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/* Type of VDU: */
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value = get_value(params, "video"); /* EGA or VGA video unit */
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if (kstrcmp(value, "ega") == 0) machine.vdu_ega = TRUE;
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if (kstrcmp(value, "vga") == 0) machine.vdu_vga = machine.vdu_ega = TRUE;
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/* Initialize free memory list from size passed by boot monitor. */
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mem_init(params);
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/* Return to assembler code to switch to protected mode (if 286),
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* reload selectors and call main().
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*/
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}
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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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PRIVATE void mem_init(params)
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_CONST char *params; /* boot monitor parameters */
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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 = get_value(params, "memory"); /* get memory boot variable */
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for (i = 0; i < NR_MEMS; i++) {
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memp = &mem[i]; /* next mem chunk is stored here */
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base = size = 0; /* initialize next base:size pair */
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if (*s != 0) { /* get fresh data, unless at end */
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/* Read fresh base and expect colon 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; /* terminate, should not happen */
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/* Read fresh size and expect comma or assume 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 *s=0; /* found end */
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}
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limit = base + size; /* limit is used for validity check */
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#if _WORD_SIZE == 2
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max_address = kinfo.protected ? 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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}
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}
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/*==========================================================================*
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* get_value *
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*==========================================================================*/
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PRIVATE char *get_value(params, name)
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_CONST char *params; /* boot monitor parameters */
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_CONST char *name; /* key to look up */
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{
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/* Get environment value - kernel version of getenv to avoid setting up the
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* usual environment array.
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*/
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register _CONST char *namep;
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register char *envp;
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for (envp = (char *) params; *envp != 0;) {
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for (namep = name; *namep != 0 && *namep == *envp; namep++, envp++)
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;
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if (*namep == '\0' && *envp == '=') return(envp + 1);
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while (*envp++ != 0)
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;
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}
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return(NIL_PTR);
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}
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