/* 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 <stdlib.h> #include <minix/boot.h> #include "protect.h" PRIVATE char k_environ[256]; /* environment strings passed by loader */ FORWARD _PROTOTYPE( int k_atoi, (char *s) ); /*==========================================================================* * cstart * *==========================================================================*/ PUBLIC void cstart(cs, ds, mcs, mds, parmoff, parmsize) U16_t cs, ds; /* Kernel code and data segment */ U16_t mcs, mds; /* Monitor code and data segment */ U16_t parmoff, parmsize; /* boot parameters offset and length */ { /* Perform system initializations prior to calling main(). */ register char *envp; phys_bytes mcode_base, mdata_base; unsigned mon_start; /* Record where the kernel and the monitor are. */ code_base = seg2phys(cs); data_base = seg2phys(ds); mcode_base = seg2phys(mcs); mdata_base = seg2phys(mds); /* Initialize protected mode descriptors. */ prot_init(); /* Copy the boot parameters to kernel memory. */ if (parmsize > sizeof k_environ - 2) parmsize = sizeof k_environ - 2; phys_copy(mdata_base + parmoff, vir2phys(k_environ), (phys_bytes) parmsize); /* Convert important boot environment variables. */ boot_parameters.bp_rootdev = k_atoi(k_getenv("rootdev")); boot_parameters.bp_ramimagedev = k_atoi(k_getenv("ramimagedev")); boot_parameters.bp_ramsize = k_atoi(k_getenv("ramsize")); boot_parameters.bp_processor = k_atoi(k_getenv("processor")); /* Type of VDU: */ envp = k_getenv("video"); if (strcmp(envp, "ega") == 0) ega = TRUE; if (strcmp(envp, "vga") == 0) vga = ega = TRUE; /* Memory sizes: */ low_memsize = k_atoi(k_getenv("memsize")); ext_memsize = k_atoi(k_getenv("emssize")); /* Processor? */ processor = boot_parameters.bp_processor; /* 86, 186, 286, 386, ... */ /* XT, AT or MCA bus? */ envp = k_getenv("bus"); if (envp == NIL_PTR || strcmp(envp, "at") == 0) { pc_at = TRUE; } else if (strcmp(envp, "mca") == 0) { pc_at = ps_mca = TRUE; } /* Decide if mode is protected. */ #if _WORD_SIZE == 2 protected_mode = processor >= 286; #endif /* Is there a monitor to return to? If so then keep it safe. */ if (!protected_mode) mon_return = 0; mon_start = mcode_base / 1024; if (mon_return && low_memsize > mon_start) low_memsize = mon_start; /* Return to assembler code to switch to protected mode (if 286), reload * selectors and call main(). */ } /*==========================================================================* * k_atoi * *==========================================================================*/ PRIVATE int k_atoi(s) register char *s; { /* Convert string to integer. */ return strtol(s, (char **) NULL, 10); } /*==========================================================================* * k_getenv * *==========================================================================*/ PUBLIC char *k_getenv(name) char *name; { /* Get environment value - kernel version of getenv to avoid setting up the * usual environment array. */ register 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); }