179 lines
6.3 KiB
C
Executable file
179 lines
6.3 KiB
C
Executable file
/* This file contains the C startup code for Minix on Intel processors.
|
|
* It cooperates with mpx.s to set up a good environment for main().
|
|
*
|
|
* This code runs in real mode for a 16 bit kernel and may have to switch
|
|
* to protected mode for a 286.
|
|
*
|
|
* For a 32 bit kernel this already runs in protected mode, but the selectors
|
|
* are still those given by the BIOS with interrupts disabled, so the
|
|
* descriptors need to be reloaded and interrupt descriptors made.
|
|
*/
|
|
|
|
#include "kernel.h"
|
|
#include "protect.h"
|
|
#include "proc.h"
|
|
|
|
/* Environment strings passed by loader. */
|
|
PRIVATE char k_environ[128*sizeof(char *)];
|
|
|
|
FORWARD _PROTOTYPE( void mem_init, (void) );
|
|
|
|
/*==========================================================================*
|
|
* cstart *
|
|
*==========================================================================*/
|
|
PUBLIC void cstart(cs, ds, mds, parmoff, parmsize)
|
|
U16_t cs, ds; /* kernel code and data segment */
|
|
U16_t mds; /* monitor data segment */
|
|
U16_t parmoff, parmsize; /* boot parameters offset and length */
|
|
{
|
|
/* Perform system initializations prior to calling main(). Most settings are
|
|
* determined with help of the environment strings passed by MINIX' loader.
|
|
*/
|
|
register char *envp;
|
|
unsigned mon_start;
|
|
extern int etext, end;
|
|
|
|
/* Decide if mode is protected; 386 or higher implies protected mode.
|
|
* This must be done first, because it is needed for, e.g., seg2phys().
|
|
* For 286 machines we cannot decide on protected mode, yet. This is
|
|
* done below.
|
|
*/
|
|
#if _WORD_SIZE != 2
|
|
machine.protected = 1;
|
|
#endif
|
|
|
|
/* Record where the kernel and the monitor are. */
|
|
kinfo.code_base = seg2phys(cs);
|
|
kinfo.code_size = (phys_bytes) &etext; /* size of code segment */
|
|
kinfo.data_base = seg2phys(ds);
|
|
kinfo.data_size = (phys_bytes) &end; /* size of data segment */
|
|
|
|
/* Initialize protected mode descriptors. */
|
|
prot_init();
|
|
|
|
/* Copy the boot parameters to kernel memory. */
|
|
kinfo.params_base = seg2phys(mds) + parmoff;
|
|
kinfo.params_size = MAX(parmsize,sizeof(k_environ)-2);
|
|
phys_copy(kinfo.params_base, vir2phys(k_environ), kinfo.params_size);
|
|
|
|
/* Record miscellaneous information for user-space servers. */
|
|
kstrncpy(kinfo.version, OS_RELEASE "." OS_VERSION, 6);
|
|
kinfo.proc_addr = (vir_bytes) proc;
|
|
kinfo.kmem_base = vir2phys(0);
|
|
kinfo.kmem_size = (phys_bytes) &end;
|
|
|
|
/* Processor? */
|
|
machine.processor=katoi(getkenv("processor")); /* 86, 186, 286, 386, ... */
|
|
|
|
/* Decide if mode is protected for older machines. */
|
|
#if _WORD_SIZE == 2
|
|
machine.protected = machine.processor >= 286;
|
|
#endif
|
|
if (! machine.protected) mon_return = 0;
|
|
|
|
/* XT, AT or MCA bus? */
|
|
envp = getkenv("bus");
|
|
if (envp == NIL_PTR || kstrcmp(envp, "at") == 0) {
|
|
machine.pc_at = TRUE; /* PC-AT compatible hardware */
|
|
} else if (kstrcmp(envp, "mca") == 0) {
|
|
machine.pc_at = machine.ps_mca = TRUE; /* PS/2 with micro channel */
|
|
}
|
|
|
|
/* Type of VDU: */
|
|
envp = getkenv("video"); /* EGA or VGA video unit */
|
|
if (kstrcmp(envp, "ega") == 0) machine.vdu_ega = TRUE;
|
|
if (kstrcmp(envp, "vga") == 0) machine.vdu_vga = machine.vdu_ega = TRUE;
|
|
|
|
/* Initialize free memory list from size passed by boot monitor. */
|
|
mem_init();
|
|
|
|
/* Return to assembler code to switch to protected mode (if 286),
|
|
* reload selectors and call main().
|
|
*/
|
|
}
|
|
|
|
|
|
|
|
/* In real mode only 1M can be addressed, and in 16-bit protected we can go
|
|
* no further than we can count in clicks. (The 286 is further limited by
|
|
* its 24 bit address bus, but we can assume in that case that no more than
|
|
* 16M memory is reported by the BIOS.)
|
|
*/
|
|
#define MAX_REAL 0x00100000L
|
|
#define MAX_16BIT (0xFFF0L << CLICK_SHIFT)
|
|
|
|
/*=========================================================================*
|
|
* mem_init *
|
|
*=========================================================================*/
|
|
PRIVATE void mem_init()
|
|
{
|
|
/* Initialize the free memory list from the 'memory' boot variable. Translate
|
|
* the byte offsets and sizes in this list to clicks, properly truncated. Also
|
|
* make sure that we don't exceed the maximum address space of the 286 or the
|
|
* 8086, i.e. when running in 16-bit protected mode or real mode.
|
|
*/
|
|
long base, size, limit;
|
|
char *s, *end; /* use to parse boot variable */
|
|
int i;
|
|
struct memory *memp;
|
|
#if _WORD_SIZE == 2
|
|
unsigned long max_address;
|
|
#endif
|
|
|
|
/* The available memory is determined by MINIX' boot loader as a list of
|
|
* (base:size)-pairs in boothead.s. The 'memory' boot variable is set in
|
|
* in boot.s. The format is "b0:s0,b1:s1,b2:s2", where b0:s0 is low mem,
|
|
* b1:s1 is mem between 1M and 16M, b2:s2 is mem above 16M. Pairs b1:s1
|
|
* and b2:s2 are combined if the memory is adjacent.
|
|
*/
|
|
s = getkenv("memory"); /* get memory boot variable */
|
|
for (i = 0; i < NR_MEMS; i++) {
|
|
memp = &mem[i]; /* result is stored here */
|
|
base = size = 0;
|
|
if (*s != 0) { /* end of boot variable */
|
|
/* Expect base to be read (end != s) and ':' as next char. */
|
|
base = kstrtoul(s, &end, 0x10); /* get number */
|
|
if (end != s && *end == ':') s = ++end; /* skip ':' */
|
|
else *s=0; /* fake end for next; should not happen */
|
|
/* Expect size to be read and skip ',', unless at end. */
|
|
size = kstrtoul(s, &end, 0x10); /* get number */
|
|
if (end != s && *end == ',') s = ++end; /* skip ',' */
|
|
else if (end != s && *end == 0) s = end; /* end found */
|
|
else *s=0; /* fake end for next; should not happen */
|
|
}
|
|
limit = base + size;
|
|
#if _WORD_SIZE == 2
|
|
max_address = kinfo.protected ? MAX_16BIT : MAX_REAL;
|
|
if (limit > max_address) limit = max_address;
|
|
#endif
|
|
base = (base + CLICK_SIZE-1) & ~(long)(CLICK_SIZE-1);
|
|
limit &= ~(long)(CLICK_SIZE-1);
|
|
if (limit <= base) continue;
|
|
memp->base = base >> CLICK_SHIFT;
|
|
memp->size = (limit - base) >> CLICK_SHIFT;
|
|
}
|
|
}
|
|
|
|
|
|
/*==========================================================================*
|
|
* getkenv *
|
|
*==========================================================================*/
|
|
PUBLIC char *getkenv(name)
|
|
_CONST char *name;
|
|
{
|
|
/* Get environment value - kernel version of getenv to avoid setting up the
|
|
* usual environment array.
|
|
*/
|
|
register _CONST char *namep;
|
|
register char *envp;
|
|
|
|
for (envp = k_environ; *envp != 0;) {
|
|
for (namep = name; *namep != 0 && *namep == *envp; namep++, envp++)
|
|
;
|
|
if (*namep == '\0' && *envp == '=') return(envp + 1);
|
|
while (*envp++ != 0)
|
|
;
|
|
}
|
|
return(NIL_PTR);
|
|
}
|