linux/arch/x86/boot/edd.c
Vivek Goyal c041b5ad86 x86, boot: Create a separate string.h file to provide standard string functions
Create a separate arch/x86/boot/string.h file to provide declaration of
some of the common string functions.

By default memcpy, memset and memcmp functions will default to gcc
builtin functions. If code wants to use an optimized version of any
of these functions, they need to #undef the respective macro and link
against a local file providing definition of undefed function.

For example, arch/x86/boot/* code links against copy.S to get memcpy()
and memcmp() definitions. arch/86/boot/compressed/* links against
compressed/string.c.

There are quite a few places in arch/x86/ where these functions are
used. Idea is to try to consilidate  their declaration and possibly
definitions so that it can be reused.

I am planning to reuse boot/string.h in arch/x86/purgatory/ and use
gcc builtin functions for memcpy, memset and memcmp.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Link: http://lkml.kernel.org/r/1395170800-11059-3-git-send-email-vgoyal@redhat.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-03-19 15:43:45 -07:00

183 lines
4.1 KiB
C

/* -*- 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>
#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