446 lines
12 KiB
C
446 lines
12 KiB
C
/*
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* Copyright (C) 2007 Michael Brown <mbrown@fensystems.co.uk>.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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/**
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* @file
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*
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* Multiboot image format
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*
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*/
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#include <stdio.h>
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#include <errno.h>
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#include <assert.h>
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#include <realmode.h>
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#include <multiboot.h>
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#include <gpxe/uaccess.h>
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#include <gpxe/image.h>
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#include <gpxe/segment.h>
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#include <gpxe/memmap.h>
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#include <gpxe/elf.h>
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#include <gpxe/init.h>
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#include <gpxe/features.h>
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FEATURE ( FEATURE_IMAGE, "Multiboot", DHCP_EB_FEATURE_MULTIBOOT, 1 );
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struct image_type multiboot_image_type __image_type ( PROBE_MULTIBOOT );
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/**
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* Maximum number of modules we will allow for
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*
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* If this has bitten you: sorry. I did have a perfect scheme with a
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* dynamically allocated list of modules on the protected-mode stack,
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* but it was incompatible with some broken OSes that can only access
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* low memory at boot time (even though we kindly set up 4GB flat
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* physical addressing as per the multiboot specification.
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*
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*/
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#define MAX_MODULES 8
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/**
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* Maximum combined length of command lines
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*
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* Again; sorry. Some broken OSes zero out any non-base memory that
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* isn't part of the loaded module set, so we can't just use
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* virt_to_phys(cmdline) to point to the command lines, even though
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* this would comply with the Multiboot spec.
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*/
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#define MB_MAX_CMDLINE 512
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/** Multiboot flags that we support */
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#define MB_SUPPORTED_FLAGS ( MB_FLAG_PGALIGN | MB_FLAG_MEMMAP | \
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MB_FLAG_VIDMODE | MB_FLAG_RAW )
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/** Compulsory feature multiboot flags */
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#define MB_COMPULSORY_FLAGS 0x0000ffff
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/** Optional feature multiboot flags */
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#define MB_OPTIONAL_FLAGS 0xffff0000
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/**
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* Multiboot flags that we don't support
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*
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* We only care about the compulsory feature flags (bits 0-15); we are
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* allowed to ignore the optional feature flags.
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*/
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#define MB_UNSUPPORTED_FLAGS ( MB_COMPULSORY_FLAGS & ~MB_SUPPORTED_FLAGS )
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/** A multiboot header descriptor */
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struct multiboot_header_info {
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/** The actual multiboot header */
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struct multiboot_header mb;
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/** Offset of header within the multiboot image */
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size_t offset;
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};
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/** Multiboot module command lines */
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static char __bss16_array ( mb_cmdlines, [MB_MAX_CMDLINE] );
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#define mb_cmdlines __use_data16 ( mb_cmdlines )
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/** Offset within module command lines */
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static unsigned int mb_cmdline_offset;
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/**
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* Build multiboot memory map
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*
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* @v image Multiboot image
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* @v mbinfo Multiboot information structure
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* @v mbmemmap Multiboot memory map
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* @v limit Maxmimum number of memory map entries
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*/
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static void multiboot_build_memmap ( struct image *image,
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struct multiboot_info *mbinfo,
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struct multiboot_memory_map *mbmemmap,
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unsigned int limit ) {
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struct memory_map memmap;
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unsigned int i;
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/* Get memory map */
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get_memmap ( &memmap );
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/* Translate into multiboot format */
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memset ( mbmemmap, 0, sizeof ( *mbmemmap ) );
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for ( i = 0 ; i < memmap.count ; i++ ) {
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if ( i >= limit ) {
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DBGC ( image, "MULTIBOOT %p limit of %d memmap "
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"entries reached\n", image, limit );
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break;
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}
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mbmemmap[i].size = ( sizeof ( mbmemmap[i] ) -
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sizeof ( mbmemmap[i].size ) );
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mbmemmap[i].base_addr = memmap.regions[i].start;
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mbmemmap[i].length = ( memmap.regions[i].end -
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memmap.regions[i].start );
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mbmemmap[i].type = MBMEM_RAM;
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mbinfo->mmap_length += sizeof ( mbmemmap[i] );
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if ( memmap.regions[i].start == 0 )
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mbinfo->mem_lower = ( memmap.regions[i].end / 1024 );
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if ( memmap.regions[i].start == 0x100000 )
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mbinfo->mem_upper = ( ( memmap.regions[i].end -
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0x100000 ) / 1024 );
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}
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}
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/**
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* Add command line in base memory
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*
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* @v cmdline Command line
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* @ret physaddr Physical address of command line
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*/
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physaddr_t multiboot_add_cmdline ( const char *cmdline ) {
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char *mb_cmdline;
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if ( ! cmdline )
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cmdline = "";
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/* Copy command line to base memory buffer */
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mb_cmdline = ( mb_cmdlines + mb_cmdline_offset );
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mb_cmdline_offset +=
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( snprintf ( mb_cmdline,
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( sizeof ( mb_cmdlines ) - mb_cmdline_offset ),
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"%s", cmdline ) + 1 );
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/* Truncate to terminating NUL in buffer if necessary */
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if ( mb_cmdline_offset > sizeof ( mb_cmdlines ) )
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mb_cmdline_offset = ( sizeof ( mb_cmdlines ) - 1 );
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return virt_to_phys ( mb_cmdline );
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}
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/**
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* Build multiboot module list
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*
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* @v image Multiboot image
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* @v modules Module list to fill, or NULL
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* @ret count Number of modules
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*/
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static unsigned int
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multiboot_build_module_list ( struct image *image,
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struct multiboot_module *modules,
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unsigned int limit ) {
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struct image *module_image;
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struct multiboot_module *module;
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unsigned int count = 0;
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unsigned int insert;
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physaddr_t start;
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physaddr_t end;
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unsigned int i;
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/* Add each image as a multiboot module */
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for_each_image ( module_image ) {
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if ( count >= limit ) {
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DBGC ( image, "MULTIBOOT %p limit of %d modules "
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"reached\n", image, limit );
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break;
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}
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/* Do not include kernel image itself as a module */
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if ( module_image == image )
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continue;
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/* At least some OSes expect the multiboot modules to
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* be in ascending order, so we have to support it.
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*/
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start = user_to_phys ( module_image->data, 0 );
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end = user_to_phys ( module_image->data, module_image->len );
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for ( insert = 0 ; insert < count ; insert++ ) {
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if ( start < modules[insert].mod_start )
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break;
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}
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module = &modules[insert];
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memmove ( ( module + 1 ), module,
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( ( count - insert ) * sizeof ( *module ) ) );
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module->mod_start = start;
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module->mod_end = end;
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module->string =
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multiboot_add_cmdline ( module_image->cmdline );
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module->reserved = 0;
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/* We promise to page-align modules */
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assert ( ( module->mod_start & 0xfff ) == 0 );
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count++;
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}
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/* Dump module configuration */
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for ( i = 0 ; i < count ; i++ ) {
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DBGC ( image, "MULTIBOOT %p module %d is [%lx,%lx)\n",
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image, i, modules[i].mod_start,
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modules[i].mod_end );
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}
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return count;
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}
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/**
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* The multiboot information structure
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*
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* Kept in base memory because some OSes won't find it elsewhere,
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* along with the other structures belonging to the Multiboot
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* information table.
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*/
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static struct multiboot_info __bss16 ( mbinfo );
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#define mbinfo __use_data16 ( mbinfo )
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/** The multiboot bootloader name */
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static char __data16_array ( mb_bootloader_name, [] ) = "gPXE " VERSION;
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#define mb_bootloader_name __use_data16 ( mb_bootloader_name )
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/** The multiboot memory map */
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static struct multiboot_memory_map
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__bss16_array ( mbmemmap, [MAX_MEMORY_REGIONS] );
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#define mbmemmap __use_data16 ( mbmemmap )
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/** The multiboot module list */
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static struct multiboot_module __bss16_array ( mbmodules, [MAX_MODULES] );
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#define mbmodules __use_data16 ( mbmodules )
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/**
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* Execute multiboot image
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*
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* @v image Multiboot image
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* @ret rc Return status code
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*/
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static int multiboot_exec ( struct image *image ) {
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physaddr_t entry = image->priv.phys;
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/* Populate multiboot information structure */
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memset ( &mbinfo, 0, sizeof ( mbinfo ) );
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mbinfo.flags = ( MBI_FLAG_LOADER | MBI_FLAG_MEM | MBI_FLAG_MMAP |
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MBI_FLAG_CMDLINE | MBI_FLAG_MODS );
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multiboot_build_memmap ( image, &mbinfo, mbmemmap,
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( sizeof(mbmemmap) / sizeof(mbmemmap[0]) ) );
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mb_cmdline_offset = 0;
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mbinfo.cmdline = multiboot_add_cmdline ( image->cmdline );
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mbinfo.mods_count = multiboot_build_module_list ( image, mbmodules,
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( sizeof(mbmodules) / sizeof(mbmodules[0]) ) );
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mbinfo.mods_addr = virt_to_phys ( mbmodules );
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mbinfo.mmap_addr = virt_to_phys ( mbmemmap );
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mbinfo.boot_loader_name = virt_to_phys ( mb_bootloader_name );
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/* Multiboot images may not return and have no callback
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* interface, so shut everything down prior to booting the OS.
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*/
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shutdown();
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/* Jump to OS with flat physical addressing */
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__asm__ __volatile__ ( PHYS_CODE ( "call *%%edi\n\t" )
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: : "a" ( MULTIBOOT_BOOTLOADER_MAGIC ),
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"b" ( virt_to_phys ( &mbinfo ) ),
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"D" ( entry )
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: "ecx", "edx", "esi", "ebp", "memory" );
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DBGC ( image, "MULTIBOOT %p returned\n", image );
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/* It isn't safe to continue after calling shutdown() */
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while ( 1 ) {}
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return -ECANCELED; /* -EIMPOSSIBLE, anyone? */
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}
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/**
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* Find multiboot header
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*
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* @v image Multiboot file
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* @v hdr Multiboot header descriptor to fill in
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* @ret rc Return status code
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*/
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static int multiboot_find_header ( struct image *image,
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struct multiboot_header_info *hdr ) {
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uint32_t buf[64];
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size_t offset;
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unsigned int buf_idx;
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uint32_t checksum;
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/* Scan through first 8kB of image file 256 bytes at a time.
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* (Use the buffering to avoid the overhead of a
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* copy_from_user() for every dword.)
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*/
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for ( offset = 0 ; offset < 8192 ; offset += sizeof ( buf[0] ) ) {
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/* Check for end of image */
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if ( offset > image->len )
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break;
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/* Refill buffer if applicable */
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buf_idx = ( ( offset % sizeof ( buf ) ) / sizeof ( buf[0] ) );
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if ( buf_idx == 0 ) {
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copy_from_user ( buf, image->data, offset,
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sizeof ( buf ) );
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}
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/* Check signature */
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if ( buf[buf_idx] != MULTIBOOT_HEADER_MAGIC )
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continue;
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/* Copy header and verify checksum */
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copy_from_user ( &hdr->mb, image->data, offset,
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sizeof ( hdr->mb ) );
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checksum = ( hdr->mb.magic + hdr->mb.flags +
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hdr->mb.checksum );
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if ( checksum != 0 )
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continue;
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/* Record offset of multiboot header and return */
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hdr->offset = offset;
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return 0;
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}
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/* No multiboot header found */
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return -ENOEXEC;
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}
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/**
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* Load raw multiboot image into memory
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*
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* @v image Multiboot file
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* @v hdr Multiboot header descriptor
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* @ret rc Return status code
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*/
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static int multiboot_load_raw ( struct image *image,
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struct multiboot_header_info *hdr ) {
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size_t offset;
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size_t filesz;
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size_t memsz;
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userptr_t buffer;
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int rc;
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/* Verify and prepare segment */
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offset = ( hdr->offset - hdr->mb.header_addr + hdr->mb.load_addr );
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filesz = ( hdr->mb.load_end_addr - hdr->mb.load_addr );
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memsz = ( hdr->mb.bss_end_addr - hdr->mb.load_addr );
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buffer = phys_to_user ( hdr->mb.load_addr );
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if ( ( rc = prep_segment ( buffer, filesz, memsz ) ) != 0 ) {
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DBGC ( image, "MULTIBOOT %p could not prepare segment: %s\n",
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image, strerror ( rc ) );
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return rc;
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}
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/* Copy image to segment */
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memcpy_user ( buffer, 0, image->data, offset, filesz );
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/* Record execution entry point in image private data field */
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image->priv.phys = hdr->mb.entry_addr;
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return 0;
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}
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/**
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* Load ELF multiboot image into memory
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*
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* @v image Multiboot file
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* @ret rc Return status code
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*/
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static int multiboot_load_elf ( struct image *image ) {
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int rc;
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/* Load ELF image*/
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if ( ( rc = elf_load ( image ) ) != 0 ) {
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DBGC ( image, "MULTIBOOT %p ELF image failed to load: %s\n",
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image, strerror ( rc ) );
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return rc;
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}
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return 0;
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}
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/**
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* Load multiboot image into memory
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*
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* @v image Multiboot file
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* @ret rc Return status code
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*/
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static int multiboot_load ( struct image *image ) {
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struct multiboot_header_info hdr;
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int rc;
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/* Locate multiboot header, if present */
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if ( ( rc = multiboot_find_header ( image, &hdr ) ) != 0 ) {
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DBGC ( image, "MULTIBOOT %p has no multiboot header\n",
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image );
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return rc;
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}
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DBGC ( image, "MULTIBOOT %p found header with flags %08lx\n",
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image, hdr.mb.flags );
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/* This is a multiboot image, valid or otherwise */
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if ( ! image->type )
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image->type = &multiboot_image_type;
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/* Abort if we detect flags that we cannot support */
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if ( hdr.mb.flags & MB_UNSUPPORTED_FLAGS ) {
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DBGC ( image, "MULTIBOOT %p flags %08lx not supported\n",
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image, ( hdr.mb.flags & MB_UNSUPPORTED_FLAGS ) );
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return -ENOTSUP;
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}
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/* Load the actual image */
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if ( hdr.mb.flags & MB_FLAG_RAW ) {
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if ( ( rc = multiboot_load_raw ( image, &hdr ) ) != 0 )
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return rc;
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} else {
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if ( ( rc = multiboot_load_elf ( image ) ) != 0 )
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return rc;
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}
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return 0;
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}
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/** Multiboot image type */
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struct image_type multiboot_image_type __image_type ( PROBE_MULTIBOOT ) = {
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.name = "Multiboot",
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.load = multiboot_load,
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.exec = multiboot_exec,
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};
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