/* -*- linux-c -*- ------------------------------------------------------- * * * Copyright (C) 1991, 1992 Linus Torvalds * Copyright 2007 rPath, Inc. - All Rights Reserved * Copyright 2009 Intel Corporation; author H. Peter Anvin * * 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) { struct biosregs ireg, oreg; initregs(&ireg); ireg.ax = 0x0201; /* Legacy Read, one sector */ ireg.cx = 0x0001; /* Sector 0-0-1 */ ireg.dl = devno; ireg.bx = (size_t)buf; intcall(0x13, &ireg, &oreg); return -(oreg.eflags & X86_EFLAGS_CF); /* 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[]; u16 mbr_magic; 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; memset(mbrbuf_ptr, 0, sector_size); if (read_mbr(devno, mbrbuf_ptr)) return -1; *mbrsig = *(u32 *)&mbrbuf_ptr[EDD_MBR_SIG_OFFSET]; mbr_magic = *(u16 *)&mbrbuf_ptr[510]; /* check for valid MBR magic */ return mbr_magic == 0xAA55 ? 0 : -1; } static int get_edd_info(u8 devno, struct edd_info *ei) { struct biosregs ireg, oreg; memset(ei, 0, sizeof *ei); /* Check Extensions Present */ initregs(&ireg); ireg.ah = 0x41; ireg.bx = EDDMAGIC1; ireg.dl = devno; intcall(0x13, &ireg, &oreg); if (oreg.eflags & X86_EFLAGS_CF) return -1; /* No extended information */ if (oreg.bx != EDDMAGIC2) return -1; ei->device = devno; ei->version = oreg.ah; /* EDD version number */ ei->interface_support = oreg.cx; /* EDD functionality subsets */ /* Extended Get Device Parameters */ ei->params.length = sizeof(ei->params); ireg.ah = 0x48; ireg.si = (size_t)&ei->params; intcall(0x13, &ireg, &oreg); /* Get legacy CHS parameters */ /* Ralf Brown recommends setting ES:DI to 0:0 */ ireg.ah = 0x08; ireg.es = 0; intcall(0x13, &ireg, &oreg); if (!(oreg.eflags & X86_EFLAGS_CF)) { ei->legacy_max_cylinder = oreg.ch + ((oreg.cl & 0xc0) << 2); ei->legacy_max_head = oreg.dh; ei->legacy_sectors_per_track = oreg.cl & 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