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https://gitlab.com/qemu-project/openbios.git
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dfd35a78c0
The current SVN version currently fails to work on machines that have strict alignment requirements, for example the SPARC target. This is due to the way the struct fat_bpb in fs/grubfs/fat.h is defined and accessed (through FAT_CVT_U16) to avoid padding. Some 16 bits fields like bytes_per_sect are thus accessed unaligned. The patch below takes the same approach as for other structures in openbios, it declares the structure as packed, and lets GCC do the right things to access those unaligned field. git-svn-id: svn://coreboot.org/openbios/openbios-devel@122 f158a5a8-5612-0410-a976-696ce0be7e32
99 lines
3.3 KiB
C
99 lines
3.3 KiB
C
/*
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* GRUB -- GRand Unified Bootloader
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* Copyright (C) 2001 Free Software Foundation, Inc.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU 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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* Defines for the FAT BIOS Parameter Block (embedded in the first block
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* of the partition.
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*/
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typedef __signed__ char __s8;
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typedef unsigned char __u8;
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typedef __signed__ short __s16;
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typedef unsigned short __u16;
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typedef __signed__ int __s32;
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typedef unsigned int __u32;
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/* Note that some shorts are not aligned, and must therefore
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* be declared as array of two bytes.
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*/
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struct fat_bpb {
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__s8 ignored[3]; /* Boot strap short or near jump */
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__s8 system_id[8]; /* Name - can be used to special case
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partition manager volumes */
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__u16 bytes_per_sect; /* bytes per logical sector */
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__u8 sects_per_clust;/* sectors/cluster */
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__u16 reserved_sects; /* reserved sectors */
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__u8 num_fats; /* number of FATs */
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__u16 dir_entries; /* root directory entries */
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__u16 short_sectors; /* number of sectors */
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__u8 media; /* media code (unused) */
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__u16 fat_length; /* sectors/FAT */
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__u16 secs_track; /* sectors per track */
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__u16 heads; /* number of heads */
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__u32 hidden; /* hidden sectors (unused) */
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__u32 long_sectors; /* number of sectors (if short_sectors == 0) */
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/* The following fields are only used by FAT32 */
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__u32 fat32_length; /* sectors/FAT */
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__u16 flags; /* bit 8: fat mirroring, low 4: active fat */
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__u16 version; /* major, minor filesystem version */
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__u32 root_cluster; /* first cluster in root directory */
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__u16 info_sector; /* filesystem info sector */
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__u16 backup_boot; /* backup boot sector */
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__u16 reserved2[6]; /* Unused */
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} __attribute__ ((packed));
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/*
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* Defines how to differentiate a 12-bit and 16-bit FAT.
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*/
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#define FAT_MAX_12BIT_CLUST 4087 /* 4085 + 2 */
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/*
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* Defines for the file "attribute" byte
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*/
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#define FAT_ATTRIB_OK_MASK 0x37
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#define FAT_ATTRIB_NOT_OK_MASK 0xC8
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#define FAT_ATTRIB_DIR 0x10
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#define FAT_ATTRIB_LONGNAME 0x0F
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/*
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* Defines for FAT directory entries
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*/
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#define FAT_DIRENTRY_LENGTH 32
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#define FAT_DIRENTRY_ATTRIB(entry) \
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(*((unsigned char *) (entry+11)))
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#define FAT_DIRENTRY_VALID(entry) \
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( ((*((unsigned char *) entry)) != 0) \
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&& ((*((unsigned char *) entry)) != 0xE5) \
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&& !(FAT_DIRENTRY_ATTRIB(entry) & FAT_ATTRIB_NOT_OK_MASK) )
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#define FAT_DIRENTRY_FIRST_CLUSTER(entry) \
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((*((unsigned short *) (entry+26)))+(*((unsigned short *) (entry+20)) << 16))
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#define FAT_DIRENTRY_FILELENGTH(entry) \
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(*((unsigned long *) (entry+28)))
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#define FAT_LONGDIR_ID(entry) \
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(*((unsigned char *) (entry)))
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#define FAT_LONGDIR_ALIASCHECKSUM(entry) \
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(*((unsigned char *) (entry+13)))
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