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[/] [or1k_soc_on_altera_embedded_dev_kit/] [trunk/] [linux-2.6/] [linux-2.6.24/] [arch/] [x86/] [boot/] [edd.c] - Rev 3
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/* -*- 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. * * ----------------------------------------------------------------------- */ /* * arch/i386/boot/edd.c * * 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; int do_edd = 1; 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_mbr = 0; else if (!strcmp(eddarg, "off")) do_edd = 0; } edp = boot_params.eddbuf; mbrptr = boot_params.edd_mbr_sig_buffer; if (!do_edd) return; for (devno = 0x80; devno < 0x80+EDD_MBR_SIG_MAX; devno++) { /* * Scan the BIOS-supported hard disks and query EDD * information... */ get_edd_info(devno, &ei); if (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; } } #endif