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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 | /* -*- linux-c -*- ------------------------------------------------------- * * * Copyright (C) 1991, 1992 Linus Torvalds * Copyright 2007 rPath, Inc. - All Rights Reserved * * This file is part of the Linux kernel, and is made available under * the terms of the GNU General Public License version 2. * * ----------------------------------------------------------------------- */ /* * Get EDD BIOS disk information */ #include "boot.h" #include <linux/edd.h> #if defined(CONFIG_EDD) || defined(CONFIG_EDD_MODULE) /* * Read the MBR (first sector) from a specific device. */ static int read_mbr(u8 devno, void *buf) { u16 ax, bx, cx, dx; ax = 0x0201; /* Legacy Read, one sector */ cx = 0x0001; /* Sector 0-0-1 */ dx = devno; bx = (size_t)buf; asm volatile("pushfl; stc; int $0x13; setc %%al; popfl" : "+a" (ax), "+c" (cx), "+d" (dx), "+b" (bx) : : "esi", "edi", "memory"); return -(u8)ax; /* 0 or -1 */ } static u32 read_mbr_sig(u8 devno, struct edd_info *ei, u32 *mbrsig) { int sector_size; char *mbrbuf_ptr, *mbrbuf_end; u32 buf_base, mbr_base; extern char _end[]; sector_size = ei->params.bytes_per_sector; if (!sector_size) sector_size = 512; /* Best available guess */ /* Produce a naturally aligned buffer on the heap */ buf_base = (ds() << 4) + (u32)&_end; mbr_base = (buf_base+sector_size-1) & ~(sector_size-1); mbrbuf_ptr = _end + (mbr_base-buf_base); mbrbuf_end = mbrbuf_ptr + sector_size; /* Make sure we actually have space on the heap... */ if (!(boot_params.hdr.loadflags & CAN_USE_HEAP)) return -1; if (mbrbuf_end > (char *)(size_t)boot_params.hdr.heap_end_ptr) return -1; if (read_mbr(devno, mbrbuf_ptr)) return -1; *mbrsig = *(u32 *)&mbrbuf_ptr[EDD_MBR_SIG_OFFSET]; return 0; } static int get_edd_info(u8 devno, struct edd_info *ei) { u16 ax, bx, cx, dx, di; memset(ei, 0, sizeof *ei); /* Check Extensions Present */ ax = 0x4100; bx = EDDMAGIC1; dx = devno; asm("pushfl; stc; int $0x13; setc %%al; popfl" : "+a" (ax), "+b" (bx), "=c" (cx), "+d" (dx) : : "esi", "edi"); if ((u8)ax) return -1; /* No extended information */ if (bx != EDDMAGIC2) return -1; ei->device = devno; ei->version = ax >> 8; /* EDD version number */ ei->interface_support = cx; /* EDD functionality subsets */ /* Extended Get Device Parameters */ ei->params.length = sizeof(ei->params); ax = 0x4800; dx = devno; asm("pushfl; int $0x13; popfl" : "+a" (ax), "+d" (dx), "=m" (ei->params) : "S" (&ei->params) : "ebx", "ecx", "edi"); /* Get legacy CHS parameters */ /* Ralf Brown recommends setting ES:DI to 0:0 */ ax = 0x0800; dx = devno; di = 0; asm("pushw %%es; " "movw %%di,%%es; " "pushfl; stc; int $0x13; setc %%al; popfl; " "popw %%es" : "+a" (ax), "=b" (bx), "=c" (cx), "+d" (dx), "+D" (di) : : "esi"); if ((u8)ax == 0) { ei->legacy_max_cylinder = (cx >> 8) + ((cx & 0xc0) << 2); ei->legacy_max_head = dx >> 8; ei->legacy_sectors_per_track = cx & 0x3f; } return 0; } void query_edd(void) { char eddarg[8]; int do_mbr = 1; #ifdef CONFIG_EDD_OFF int do_edd = 0; #else int do_edd = 1; #endif int be_quiet; int devno; struct edd_info ei, *edp; u32 *mbrptr; if (cmdline_find_option("edd", eddarg, sizeof eddarg) > 0) { if (!strcmp(eddarg, "skipmbr") || !strcmp(eddarg, "skip")) { do_edd = 1; do_mbr = 0; } else if (!strcmp(eddarg, "off")) do_edd = 0; else if (!strcmp(eddarg, "on")) do_edd = 1; } be_quiet = cmdline_find_option_bool("quiet"); edp = boot_params.eddbuf; mbrptr = boot_params.edd_mbr_sig_buffer; if (!do_edd) return; /* Bugs in OnBoard or AddOnCards Bios may hang the EDD probe, * so give a hint if this happens. */ if (!be_quiet) printf("Probing EDD (edd=off to disable)... "); for (devno = 0x80; devno < 0x80+EDD_MBR_SIG_MAX; devno++) { /* * Scan the BIOS-supported hard disks and query EDD * information... */ if (!get_edd_info(devno, &ei) && boot_params.eddbuf_entries < EDDMAXNR) { memcpy(edp, &ei, sizeof ei); edp++; boot_params.eddbuf_entries++; } if (do_mbr && !read_mbr_sig(devno, &ei, mbrptr++)) boot_params.edd_mbr_sig_buf_entries = devno-0x80+1; } if (!be_quiet) printf("ok\n"); } #endif |