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180 lines
4.0 KiB
180 lines
4.0 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* -*- linux-c -*- ------------------------------------------------------- * |
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* |
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* Copyright (C) 1991, 1992 Linus Torvalds |
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* Copyright 2007 rPath, Inc. - All Rights Reserved |
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* Copyright 2009 Intel Corporation; author H. Peter Anvin |
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* |
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* ----------------------------------------------------------------------- */ |
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/* |
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* Get EDD BIOS disk information |
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*/ |
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#include "boot.h" |
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#include <linux/edd.h> |
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#include "string.h" |
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#if defined(CONFIG_EDD) || defined(CONFIG_EDD_MODULE) |
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/* |
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* Read the MBR (first sector) from a specific device. |
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*/ |
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static int read_mbr(u8 devno, void *buf) |
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{ |
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struct biosregs ireg, oreg; |
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initregs(&ireg); |
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ireg.ax = 0x0201; /* Legacy Read, one sector */ |
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ireg.cx = 0x0001; /* Sector 0-0-1 */ |
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ireg.dl = devno; |
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ireg.bx = (size_t)buf; |
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intcall(0x13, &ireg, &oreg); |
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return -(oreg.eflags & X86_EFLAGS_CF); /* 0 or -1 */ |
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} |
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static u32 read_mbr_sig(u8 devno, struct edd_info *ei, u32 *mbrsig) |
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{ |
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int sector_size; |
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char *mbrbuf_ptr, *mbrbuf_end; |
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u32 buf_base, mbr_base; |
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extern char _end[]; |
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u16 mbr_magic; |
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sector_size = ei->params.bytes_per_sector; |
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if (!sector_size) |
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sector_size = 512; /* Best available guess */ |
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/* Produce a naturally aligned buffer on the heap */ |
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buf_base = (ds() << 4) + (u32)&_end; |
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mbr_base = (buf_base+sector_size-1) & ~(sector_size-1); |
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mbrbuf_ptr = _end + (mbr_base-buf_base); |
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mbrbuf_end = mbrbuf_ptr + sector_size; |
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/* Make sure we actually have space on the heap... */ |
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if (!(boot_params.hdr.loadflags & CAN_USE_HEAP)) |
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return -1; |
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if (mbrbuf_end > (char *)(size_t)boot_params.hdr.heap_end_ptr) |
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return -1; |
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memset(mbrbuf_ptr, 0, sector_size); |
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if (read_mbr(devno, mbrbuf_ptr)) |
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return -1; |
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*mbrsig = *(u32 *)&mbrbuf_ptr[EDD_MBR_SIG_OFFSET]; |
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mbr_magic = *(u16 *)&mbrbuf_ptr[510]; |
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/* check for valid MBR magic */ |
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return mbr_magic == 0xAA55 ? 0 : -1; |
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} |
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static int get_edd_info(u8 devno, struct edd_info *ei) |
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{ |
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struct biosregs ireg, oreg; |
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memset(ei, 0, sizeof(*ei)); |
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/* Check Extensions Present */ |
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initregs(&ireg); |
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ireg.ah = 0x41; |
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ireg.bx = EDDMAGIC1; |
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ireg.dl = devno; |
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intcall(0x13, &ireg, &oreg); |
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if (oreg.eflags & X86_EFLAGS_CF) |
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return -1; /* No extended information */ |
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if (oreg.bx != EDDMAGIC2) |
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return -1; |
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ei->device = devno; |
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ei->version = oreg.ah; /* EDD version number */ |
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ei->interface_support = oreg.cx; /* EDD functionality subsets */ |
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/* Extended Get Device Parameters */ |
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ei->params.length = sizeof(ei->params); |
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ireg.ah = 0x48; |
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ireg.si = (size_t)&ei->params; |
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intcall(0x13, &ireg, &oreg); |
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/* Get legacy CHS parameters */ |
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/* Ralf Brown recommends setting ES:DI to 0:0 */ |
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ireg.ah = 0x08; |
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ireg.es = 0; |
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intcall(0x13, &ireg, &oreg); |
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if (!(oreg.eflags & X86_EFLAGS_CF)) { |
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ei->legacy_max_cylinder = oreg.ch + ((oreg.cl & 0xc0) << 2); |
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ei->legacy_max_head = oreg.dh; |
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ei->legacy_sectors_per_track = oreg.cl & 0x3f; |
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} |
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return 0; |
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} |
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void query_edd(void) |
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{ |
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char eddarg[8]; |
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int do_mbr = 1; |
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#ifdef CONFIG_EDD_OFF |
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int do_edd = 0; |
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#else |
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int do_edd = 1; |
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#endif |
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int be_quiet; |
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int devno; |
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struct edd_info ei, *edp; |
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u32 *mbrptr; |
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if (cmdline_find_option("edd", eddarg, sizeof(eddarg)) > 0) { |
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if (!strcmp(eddarg, "skipmbr") || !strcmp(eddarg, "skip")) { |
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do_edd = 1; |
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do_mbr = 0; |
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} |
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else if (!strcmp(eddarg, "off")) |
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do_edd = 0; |
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else if (!strcmp(eddarg, "on")) |
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do_edd = 1; |
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} |
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be_quiet = cmdline_find_option_bool("quiet"); |
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edp = boot_params.eddbuf; |
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mbrptr = boot_params.edd_mbr_sig_buffer; |
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if (!do_edd) |
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return; |
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/* Bugs in OnBoard or AddOnCards Bios may hang the EDD probe, |
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* so give a hint if this happens. |
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*/ |
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if (!be_quiet) |
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printf("Probing EDD (edd=off to disable)... "); |
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for (devno = 0x80; devno < 0x80+EDD_MBR_SIG_MAX; devno++) { |
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/* |
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* Scan the BIOS-supported hard disks and query EDD |
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* information... |
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*/ |
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if (!get_edd_info(devno, &ei) |
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&& boot_params.eddbuf_entries < EDDMAXNR) { |
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memcpy(edp, &ei, sizeof(ei)); |
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edp++; |
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boot_params.eddbuf_entries++; |
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} |
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if (do_mbr && !read_mbr_sig(devno, &ei, mbrptr++)) |
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boot_params.edd_mbr_sig_buf_entries = devno-0x80+1; |
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} |
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if (!be_quiet) |
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printf("ok\n"); |
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} |
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#endif
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