114 lines
4 KiB
C
Executable file
114 lines
4 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( 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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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 = MIN(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.release, OS_RELEASE, 4);
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kstrncpy(kinfo.version, OS_VERSION, 4);
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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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/* 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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/*==========================================================================*
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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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