diff options
Diffstat (limited to 'src/arch')
| -rw-r--r-- | src/arch/x86/interface/pcbios/int13.c | 56 |
1 files changed, 45 insertions, 11 deletions
diff --git a/src/arch/x86/interface/pcbios/int13.c b/src/arch/x86/interface/pcbios/int13.c index c322440e..0bc123d7 100644 --- a/src/arch/x86/interface/pcbios/int13.c +++ b/src/arch/x86/interface/pcbios/int13.c @@ -219,14 +219,13 @@ static int int13_guess_geometry_hdd ( struct san_device *sandev, void *scratch, struct master_boot_record *mbr = scratch; struct partition_table_entry *partition; unsigned int i; + unsigned int start_cylinder; + unsigned int start_head; + unsigned int start_sector; unsigned int end_head; unsigned int end_sector; int rc; - /* Default guess is xx/255/63 */ - *heads = 255; - *sectors = 63; - /* Read partition table */ if ( ( rc = sandev_rw ( sandev, 0, 1, virt_to_user ( mbr ), block_read ) ) != 0 ) { @@ -244,19 +243,54 @@ static int int13_guess_geometry_hdd ( struct san_device *sandev, void *scratch, * heads and sectors_per_track if we find any used * partitions. */ + *heads = 0; + *sectors = 0; for ( i = 0 ; i < 4 ; i++ ) { + + /* Skip empty partitions */ partition = &mbr->partitions[i]; + if ( ! partition->type ) + continue; + + /* If partition starts on cylinder 0 then we can + * unambiguously determine the number of sectors. + */ + start_cylinder = PART_CYLINDER ( partition->chs_start ); + start_head = PART_HEAD ( partition->chs_start ); + start_sector = PART_SECTOR ( partition->chs_start ); + if ( ( start_cylinder == 0 ) && ( start_head != 0 ) ) { + *sectors = ( ( partition->start + 1 - start_sector ) / + start_head ); + DBGC ( sandev, "INT13 drive %02x guessing C/H/S " + "xx/xx/%d based on partition %d\n", + sandev->drive, *sectors, ( i + 1 ) ); + } + + /* If partition ends on a higher head or sector number + * than our current guess, then increase the guess. + */ end_head = PART_HEAD ( partition->chs_end ); end_sector = PART_SECTOR ( partition->chs_end ); - if ( ! ( partition->type && end_head && end_sector ) ) - continue; - *heads = ( end_head + 1 ); - *sectors = end_sector; - DBGC ( sandev, "INT13 drive %02x guessing C/H/S xx/%d/%d based " - "on partition %d\n", - sandev->drive, *heads, *sectors, ( i + 1 ) ); + if ( ( end_head + 1 ) > *heads ) { + *heads = ( end_head + 1 ); + DBGC ( sandev, "INT13 drive %02x guessing C/H/S " + "xx/%d/xx based on partition %d\n", + sandev->drive, *heads, ( i + 1 ) ); + } + if ( end_sector > *sectors ) { + *sectors = end_sector; + DBGC ( sandev, "INT13 drive %02x guessing C/H/S " + "xx/xx/%d based on partition %d\n", + sandev->drive, *sectors, ( i + 1 ) ); + } } + /* Default guess is xx/255/63 */ + if ( ! *heads ) + *heads = 255; + if ( ! *sectors ) + *sectors = 63; + return 0; } |