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Split bootsector execution code out into bootsector.c.

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Added basic El Torito ISO image boot capability
This commit is contained in:
Michael Brown
2007-01-29 04:21:38 +00:00
parent bde8878eef
commit 2cf1e33df1
7 changed files with 610 additions and 68 deletions
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125
src/arch/i386/interface/pcbios/int13.c
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@@ -26,6 +26,7 @@
#include <realmode.h>
#include <bios.h>
#include <biosint.h>
#include <bootsector.h>
#include <int13.h>
/** @file
@@ -44,23 +45,6 @@ static struct segoff __text16 ( int13_vector );
/** Assembly wrapper */
extern void int13_wrapper ( void );
/** Vector for storing original INT 18 handler
*
* We do not chain to this vector, so there is no need to place it in
* .text16.
*/
static struct segoff int18_vector;
/** Vector for storing original INT 19 handler
*
* We do not chain to this vector, so there is no need to place it in
* .text16.
*/
static struct segoff int19_vector;
/** Restart point for INT 18 or 19 */
extern void int13_exec_fail ( void );
/** List of registered emulated drives */
static LIST_HEAD ( drives );
@@ -114,6 +98,13 @@ static int int13_rw_sectors ( struct int13_drive *drive,
unsigned int count;
userptr_t buffer;
/* Validate blocksize */
if ( blockdev->blksize != INT13_BLKSIZE ) {
DBG ( "Invalid blocksize (%zd) for non-extended read/write\n",
blockdev->blksize );
return -INT13_STATUS_INVALID;
}
/* Calculate parameters */
cylinder = ( ( ( ix86->regs.cl & 0xc0 ) << 2 ) | ix86->regs.ch );
assert ( cylinder < drive->cylinders );
@@ -129,13 +120,6 @@ static int int13_rw_sectors ( struct int13_drive *drive,
DBG ( "C/H/S %d/%d/%d = LBA %#lx <-> %04x:%04x (count %d)\n", cylinder,
head, sector, lba, ix86->segs.es, ix86->regs.bx, count );
/* Validate blocksize */
if ( blockdev->blksize != INT13_BLKSIZE ) {
DBG ( "Invalid blocksize (%zd) for non-extended read/write\n",
blockdev->blksize );
return -INT13_STATUS_INVALID;
}
/* Read from / write to block device */
if ( io ( blockdev, lba, count, buffer ) != 0 )
return -INT13_STATUS_READ_ERROR;
@@ -333,6 +317,38 @@ static int int13_get_extended_parameters ( struct int13_drive *drive,
return 0;
}
struct int13_cdrom_specification {
/** Size of packet in bytes */
uint8_t size;
/** Boot media type */
uint8_t media_type;
/** Drive number */
uint8_t drive;
};
/**
* INT 13, 4b - Get CD-ROM status / terminate emulation
*
* @v drive Emulated drive
* @v ds:si El Torito specification packet to fill in
* @ret status Status code
*/
static int int13_cdrom_status_terminate ( struct int13_drive *drive,
struct i386_all_regs *ix86 ) {
struct int13_cdrom_specification specification;
DBG ( "Get CD-ROM emulation parameters to %04x:%04x\n",
ix86->segs.ds, ix86->regs.di );
memset ( &specification, 0, sizeof ( specification ) );
specification.size = sizeof ( specification );
specification.drive = drive->drive;
copy_to_real ( ix86->segs.ds, ix86->regs.si, &specification,
sizeof ( specification ) );
return 0;
}
/**
* INT 13 handler
*
@@ -346,7 +362,7 @@ static void int13 ( struct i386_all_regs *ix86 ) {
if ( drive->drive != ix86->regs.dl )
continue;
DBG ( "INT 13,%02x (%02x): ", command, drive->drive );
DBG ( "INT 13,%04x (%02x): ", ix86->regs.ax, drive->drive );
switch ( command ) {
case INT13_RESET:
@@ -379,6 +395,9 @@ static void int13 ( struct i386_all_regs *ix86 ) {
case INT13_GET_EXTENDED_PARAMETERS:
status = int13_get_extended_parameters ( drive, ix86 );
break;
case INT13_CDROM_STATUS_TERMINATE:
status = int13_cdrom_status_terminate ( drive, ix86 );
break;
default:
DBG ( "*** Unrecognised INT 13 ***\n" );
status = -INT13_STATUS_INVALID;
@@ -398,6 +417,8 @@ static void int13 ( struct i386_all_regs *ix86 ) {
/* Set OF to indicate to wrapper not to chain this call */
ix86->flags |= OF;
break;
}
}
@@ -453,6 +474,10 @@ static void guess_int13_geometry ( struct int13_drive *drive ) {
unsigned long blocks_per_cyl;
unsigned int i;
/* Don't even try when the blksize is invalid for C/H/S access */
if ( drive->blockdev->blksize != INT13_BLKSIZE )
return;
/* Scan through partition table and modify guesses for heads
* and sectors_per_track if we find any used partitions.
*/
@@ -564,6 +589,7 @@ void unregister_int13_drive ( struct int13_drive *drive ) {
int int13_boot ( unsigned int drive ) {
int status, signature;
int discard_c, discard_d;
int rc;
DBG ( "Booting from INT 13 drive %02x\n", drive );
@@ -593,48 +619,11 @@ int int13_boot ( unsigned int drive ) {
return -ENOEXEC;
}
/* Hook INTs 18 and 19 to capture failure paths */
hook_bios_interrupt ( 0x18, ( unsigned int ) int13_exec_fail,
&int18_vector );
hook_bios_interrupt ( 0x19, ( unsigned int ) int13_exec_fail,
&int19_vector );
/* Jump to boot sector */
if ( ( rc = call_bootsector ( 0x0, 0x7c00, drive ) ) != 0 ) {
DBG ( "INT 13 drive %02x boot returned\n", drive );
return rc;
}
/* Boot the loaded sector
*
* We assume that the boot sector may completely destroy our
* real-mode stack, so we preserve everything we need in
* static storage.
*/
__asm__ __volatile__ ( REAL_CODE ( /* Save return address off-stack */
"popw %%cs:int13_saved_retaddr\n\t"
/* Save stack pointer */
"movw %%ss, %%ax\n\t"
"movw %%ax, %%cs:int13_saved_ss\n\t"
"movw %%sp, %%cs:int13_saved_sp\n\t"
/* Jump to boot sector */
"ljmp $0, $0x7c00\n\t"
/* Preserved variables */
"\nint13_saved_ss: .word 0\n\t"
"\nint13_saved_sp: .word 0\n\t"
"\nint13_saved_retaddr: .word 0\n\t"
/* Boot failure return point */
"\nint13_exec_fail:\n\t"
/* Restore stack pointer */
"movw %%cs:int13_saved_ss, %%ax\n\t"
"movw %%ax, %%ss\n\t"
"movw %%cs:int13_saved_sp, %%sp\n\t"
/* Return via saved address */
"jmp *%%cs:int13_saved_retaddr\n\t")
: "=d" ( discard_d ) : "d" ( drive )
: "eax", "ebx", "ecx", "esi", "edi", "ebp" );
DBG ( "Booted disk returned via INT 18 or 19\n" );
/* Unhook INTs 18 and 19 */
unhook_bios_interrupt ( 0x18, ( unsigned int ) int13_exec_fail,
&int18_vector );
unhook_bios_interrupt ( 0x19, ( unsigned int ) int13_exec_fail,
&int19_vector );
return -ECANCELED;
return -ECANCELED; /* -EIMPOSSIBLE */
}