diff options
Diffstat (limited to 'arch/x86/boot/edd.c')
| -rw-r--r-- | arch/x86/boot/edd.c | 180 |
1 files changed, 180 insertions, 0 deletions
diff --git a/arch/x86/boot/edd.c b/arch/x86/boot/edd.c new file mode 100644 index 0000000000..1fb4bc70ce --- /dev/null +++ b/arch/x86/boot/edd.c @@ -0,0 +1,180 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* -*- linux-c -*- ------------------------------------------------------- * + * + * Copyright (C) 1991, 1992 Linus Torvalds + * Copyright 2007 rPath, Inc. - All Rights Reserved + * Copyright 2009 Intel Corporation; author H. Peter Anvin + * + * ----------------------------------------------------------------------- */ + +/* + * Get EDD BIOS disk information + */ + +#include "boot.h" +#include <linux/edd.h> +#include "string.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 |