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pascal@19515
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1 // This file is distributed under GPL
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2
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pascal@19515
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3 #include "crtl.h"
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4 #include "common.h"
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5
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pascal@19515
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6 /***************
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7 Memory layout assumed by kernel boot process
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8 --------------------------------------------
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9 Note: claims that kernel setup is relocatable are
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10 still not 100% valid:
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11 bzImage decompressing trashes 10000-8ffff range,
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12 so rm loader -> pm kernel info is lost if it was here...
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13 So I had to stick to 90000.
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14
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15 10000000+------------------------+ <- 256m
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16 | initrd | initrd is at top of mem, but
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17 | | not higher than 256m
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18 +------------------------+
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19 +------------------------+
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20 | bzImage | bzImage is at 1m
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21 | | VCPI/XMS/64k offset tricks used...
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22 00100000+------------------------+ <- 1m
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23 | video, BIOS etc | Do not use.
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24 000A0000+------------------------+
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25 | Reserved for BIOS | Do not use. Reserved for BIOS EBDA.
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26 0009A000+------------------------+ <- stack top for kernel rm code
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27 | Cmdline |
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28 00098000+------------------------+ <- heap top for kernel rm code
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29 | Kernel setup | The kernel real-mode code.
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30 00090200+------------------------+
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31 | Kernel boot sector | The kernel legacy boot sector.
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32 00090000+------------------------+
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33 | Zapped by ungzip | Historically zImages were loaded here
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34 | (zImage once was here) | bzImages use this space for ungzipping
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35 00010000+------------------------+
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36 | Boot loader | <- Boot sector entry point 0000:7C00
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37 00001000+------------------------+
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38 | Reserved for MBR/BIOS |
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39 00000800+------------------------+
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40 | Typically used by MBR |
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41 00000600+------------------------+
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42 | BIOS use only |
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43 00000000+------------------------+
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44 */
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45
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46 struct kernelparams_t {
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47 u8 setup_sects; // 01F1 The size of the setup in sectors
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48 // boot sector is NOT included here
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49 u16 ro_flag; // 01F2 If set, the root is mounted readonly
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50 u16 syssize; // 01F4 DO NOT USE - for bootsect.S use only:
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51 // size of pm part of kernel
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52 // (in 16 byte units, rounded up)
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53 u16 swap_dev; // 01F6 DO NOT USE - obsolete
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54 u16 ram_size; // 01F8 DO NOT USE - for bootsect.S use only:
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55 // if nonzero then kernel
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56 // (driver/block/ramdisk.c: rd_load())
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57 // will try to load the contents for the ramdisk
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58 // from the "root_dev" which MUST then have the
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59 // floppyMAJOR
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60 // The file-system on that floppy must be MINIX
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61 // If rd_load() succeeds it sets the root_dev
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62 // to the ramdisk for mounting it
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63 u16 vid_mode; // 01FA Video mode control
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64 u16 root_dev; // 01FC Default root device number
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65 u16 boot_flag; // 01FE 0xAA55 magic number
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66 u16 jump; // 0200 Jump instruction
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67 u32 header; // 0202 Magic signature "HdrS"
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68 u16 version; // 0206 Boot protocol version supported
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69 u16 realmode_switch_ofs; // 0208 Hook called just before rm->pm
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70 u16 realmode_switch_seg;
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71 u16 start_sys_seg; // 020E
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72 u16 kernel_version; // 020C Points to kernel version string
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73 u8 type_of_loader; // 0210 Boot loader identifier
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74 u8 loadflags; // 0211 Boot protocol option flags
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75 u16 setup_move_size;// 0212 Move to high memory size (used with hooks)
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76 u32 code32_start; // 0214 Boot loader hook (see below)
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77 u32 initrd_buf; // 0218 initrd load address (set by boot loader)
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78 u32 initrd_size; // 021C initrd size (set by boot loader)
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79 u32 bootsect_kludge;// 0220 DO NOT USE - for bootsect.S use only
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80 u16 heap_end_ptr; // 0224 Free memory after setup end
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81 u16 pad1; // 0226 Unused
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82 u32 cmd_line_ptr; // 0228 32-bit pointer to the kernel command line
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83 u8 pad30[0x400-0x22c]; // 022C
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84 // 02D0 up to 32 20-byte mem info structs from
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85 // int 0x15 fn 0xe820
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86 }; //__attribute((packed));
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87
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88 struct first1k_t {
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pascal@19538
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89 // these two set by rm setup:
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90 u16 curr_curs; // 0000 saved cursor position
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91 u16 ext_mem_size; // 0002 extended memory size in Kb (from int 0x15 fn 0x88)
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92 u8 pad00[0x20-4];
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93 // old-style cmdline (not used in LINLD (yet?))
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94 u32 cl_magic_ofs;
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95 //u16 cl_magic; // 0020 commandline magic number (=0xA33F)
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96 //u16 cl_ofs; // 0022 commandline offset
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97 u8 pad10[0x80-0x24];
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98 // these two set by rm setup:
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99 u8 hd0_disk_par[16]; // 0080 hd0-disk-parameter from intvector 0x41
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100 u8 hd1_disk_par[16]; // 0090 hd1-disk-parameter from intvector 0x46
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101 u8 pad20[0x01e0-0xa0];
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102 // this is set by rm setup:
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103 u32 alt_mem_size; // 01E0 extended memory size in Kb (from int 0x15 fn 0xe801)
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104 u8 pad28[0x01f1-0x1e4];
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105 struct kernelparams_t params;
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106 }; //__attribute((packed));
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107
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108 #if sizeof(first1k_t)!=0x400
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109 #error BUG: Bad first1k
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110 #endif
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111
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112 const u32 HdrS = 'H' + ('d'<<8) + (u32('r')<<16) + (u32('S')<<24);
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113
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114 u16 rm_size;
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115 u8 pm_high; // @ = @rm_size + 2, see JUMP.ASM
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116 u8* rm_buf; // @ = @rm_size + 3, see JUMP.ASM
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117 u32 base_himem = _1m+_64k;
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118 extern struct image_himem pm, initrd;
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119
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120 // register value to launch the kernel real mode code
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121 #ifdef NO386
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122 static u32 csip;
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123 extern "C" u16 topseg();
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124 #else
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125 static u32 csip=0x90200000;
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126 #define topseg() 0x9000
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127 #endif
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128
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pascal@19515
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129 static const char kernel_file_error[] = "Can't use kernel file";
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130 char* load_kernel() {
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131
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132 struct image_himem *m = ±
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133 #ifdef NO386
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134 *((u16 *)&csip+1)=topseg()+0x20;
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135 #endif
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pascal@19515
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136 // Open kernel, read first kb, check it
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137 m->errmsg = kernel_file_error;
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138 open_image(kernel_name, m);
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139
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140 char *version_string;
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141 {
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142 struct first1k_t *first1k;
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143 struct kernelparams_t *kernelparams;
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144 kernelparams = &(((first1k_t*) (rm_buf = malloc_or_die(_32k)))->params);
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145 #define first1k ((first1k_t*)((u8 *)kernelparams-0x1F1))
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146 {
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147 u16 rm_seek;
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148
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149 // Do not use malloc below until heap_top adjustment (see <*>)
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150 if (read(m->fd, rm_buf, rm_seek=0x400) != 0x400) {
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151 readfail:
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152 die(kernel_file_error);
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153 }
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154
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155 if(kernelparams->setup_sects == 0) {
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156 #if 1
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157 if(* (int *) &first1k->pad10[0x3F-0x24] == 0x3AE8) {
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158 lseekset(pm.fd,rm_seek=0x200);
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159 csip+=0xFFE00042;
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160 }
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161 else
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162 #endif
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163 kernelparams->setup_sects=4;
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164 }
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165 if((kernelparams->setup_sects)>=(_32k/512) || // 0th sector not counted
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166 kernelparams->boot_flag != 0xAA55)
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167 die("It's not a kernel");
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168 heap_top = rm_buf+(rm_size=0x200*(kernelparams->setup_sects+1)); // <*>
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169
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pascal@19515
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170 // Read remaining rm loader
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171
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pascal@19515
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172 {
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173 u16 cnt = rm_size-rm_seek;
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174 if (read(m->fd, rm_buf+rm_seek, cnt) != cnt) goto readfail;
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175 }
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176 }
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177
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pascal@19515
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178 // Tell rm loader some info
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179
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180 if(vid_mode) kernelparams->vid_mode = vid_mode;
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181 if(root_dev) kernelparams->root_dev = root_dev;
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182 version_string = 0;
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183
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184 #if 1
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185 if(kernelparams->header == HdrS) { // starting linux 1.3.73
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186 if(kernelparams->loadflags & 1) {
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187 #else
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188 if((kernelparams->header != HdrS) || (kernelparams->loadflags & 1) == 0)
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189 die("I can't load bzImage low");
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190 {
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191 {
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192 #endif
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193 pm_high++;
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194
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pascal@19515
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195 // Hook on int15 to work around fn 88 DOS breakage
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196 hook_int15_88();
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197
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198 // * will be called just before rm -> pm
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199 extern void far last_ditch();
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200 kernelparams->realmode_switch_ofs = ofs((void *)last_ditch);
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201 kernelparams->realmode_switch_seg = seg(last_ditch);
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202 }
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pascal@19538
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203 if(kernelparams->kernel_version)
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204 version_string = (char *) first1k+kernelparams->kernel_version+0x200;
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205 kernelparams->type_of_loader = 0xff; // kernel do not know us (yet :-)
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206 if(kernelparams->version >= 0x201) {
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pascal@19515
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207 // * offset limit of the setup heap
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208 // heap_end_ptr appears to be relative to the start of setup (ofs 0x0200)
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209 kernelparams->heap_end_ptr = _32k-0x0200;
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210 kernelparams->loadflags |= 0x80; // says to rm loader it's ok to use heap
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211 }
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pascal@19515
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212 // * if we will ever stop moving ourself to 0x90000
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213 // we must say setup.S how much to move
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214 //kernelparams->setup_move_size = _32k;
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215 if(kernelparams->version >= 0x202) { // starting linux 2.4.0-test3-pre3
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216 kernelparams->cmd_line_ptr = (((u32)(topseg()+0x0800))<<4);
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217 goto cmd_line_ok;
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218 }
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219 }
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220 first1k->cl_magic_ofs = 0x8000A33F;
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221 }
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222
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223 cmd_line_ok:
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224 // Check and enable A20 if needed
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225 enable_a20_or_die();
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226
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pascal@19515
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227 // Read remaining kernel (pm part)
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pascal@19515
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228 // Try to load kernel high, maybe even blindly storing it
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pascal@19515
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229 // in unallocated memory as a last resort
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230
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231 {
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232 struct image_himem *m = ±
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233 m->fallback = (u32((u16(_CS)+0x1FFF)&0xF000)<<4);
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234 m->size -= rm_size;
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235 m->chunk_size -= rm_size;
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236 if((u16)((m->fallback+m->size)>>4) > topseg() || pm_high) {
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237 m->fallback = base_himem;
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238 }
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239
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240 load_image(m);
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241 }
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pascal@19515
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242 return version_string;
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243 }
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pascal@19515
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244
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pascal@19515
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245 // Read initrd if needed
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246
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247 void load_initrd() {
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248 struct image_himem *m = &initrd;
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249 m->errmsg = "Can't use initrd file";
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250 if (!initrd_name && !m->fd) return;
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251
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252 open_image(initrd_name, m);
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253
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254 if ((m->fallback=(memtop()-m->size)&(~PAGE_MASK)) < pm.fallback+pm.size) {
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255 close(m->fd);
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256 puts(m->errmsg);
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257 return;
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pascal@19515
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258 }
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pascal@19515
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259
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pascal@19515
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260 load_image(m);
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pascal@19571
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261 struct kernelparams_t *kernelparams = &(((first1k_t*) rm_buf)->params);
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pascal@19538
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262 if(kernelparams->header == HdrS) {
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263 kernelparams->initrd_buf = m->fallback;
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pascal@19538
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264 kernelparams->initrd_size = m->size;
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pascal@19515
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265 }
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pascal@19515
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266 }
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pascal@19515
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267
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pascal@19515
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268 void boot_kernel() {
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pascal@19515
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269
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pascal@19515
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270 // Shrink stack: we won't need much of it now and have no malloc() plans
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pascal@19515
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271 {
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272 u16 new_SP=u16(heap_top)+0x100;
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pascal@19515
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273 if(_SP>new_SP) _SP=new_SP;
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pascal@19515
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274 }
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pascal@19571
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275 if( (u16(_SP)>>4)+u16(_CS) >= topseg() ) {
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pascal@19515
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276 // Oops! We can stomp on our toes... better stop now
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277 die("Loaded too close to 9000:0");
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pascal@19515
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278 }
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279
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pascal@19571
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280 // Move rm loader & commandline to 0x90000, Jump to kernel rm code
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281 set_sregs_jump_seg_ofs(csip);
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pascal@19515
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282 }
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