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hidden sector count fixes for fat12_16_dbr, fat32_dbr, exfat_dbr and ntfs_dbr #219

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hidden sector count fixes for fat12_16_dbr, fat32_dbr, exfat_dbr and ntfs_dbr #219

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ff7f130
applied the hidden sector count fix to fat32_dbr
Nov 11, 2019
98f3e09
applied the hidden sector count fix to fat12_16_dbr
Nov 11, 2019
aaf6c6b
applied the hidden sector count fix to exfat_dbr
Nov 11, 2019
5650e77
applied the hidden sector count fix to ntfs_dbr
Nov 11, 2019
3af1b6b
prefactor: optimized ntfs_dbr for size and moved some code to the 2nd…
Nov 11, 2019
1a24c11
made ntfsg.S work with sectors_per_track=0 and number_of_heads=0, the…
Nov 11, 2019
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52 changes: 24 additions & 28 deletions stage2/grldrstart.S
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Original file line number Diff line number Diff line change
Expand Up @@ -1044,6 +1044,7 @@ Entry_32:
movb $0x41, %ah
movw $0x55AA, %bx
int $0x13
movl 0x8(%si), %eax /* partition_table_entry.start_sector_ofs (LBA) */
popw %ds
jc 1f /* No EBIOS */
cmpw $0xAA55, %bx
Expand All @@ -1052,6 +1053,7 @@ Entry_32:
jnc 1f /* No EBIOS */
/* EBIOS supported */
movb $0x42, (ebios_32 - 1 - Entry_32 + 0x7c00)
movl %eax, 0x1c(%bp) /* copy partition_table_entry.start_sector_ofs to hidden sectors */
1:
// movb (Loadusb_32 - Entry_32 + 0x7c00 +1), %al
// decb %al //al=1,When dl = 00 load
Expand Down Expand Up @@ -1473,6 +1475,7 @@ Entry_12_16:
movw $0x7c00, %bp
movw %bp, %sp
movw %ax, %ss /* stack and BP-relative moves up, too */
pushl 0x8(%si) /* partition_table_entry.start_sector_ofs (LBA) */
movw %ax, %ds
movw %ax, %es
sti /* after stack setup, we can use stack */
Expand All @@ -1487,13 +1490,15 @@ Entry_12_16:
int $0x13
popw %es
popw %ds
popl %eax /* partition_table_entry.start_sector_ofs (LBA) */
jc 1f /* No EBIOS */
cmpw $0xAA55, %bx
jne 1f /* No EBIOS */
rorb $1, %cl
jnc 1f /* No EBIOS */
/* EBIOS supported */
movb $0x42, (ebios_12_16 - 1 - Entry_12_16 + 0x7c00)
movl %eax, 0x1c(%bp) /* copy partition_table_entry.start_sector_ofs to hidden sectors */
1:
/* GET DRIVE PARMS: Calculate start of some disk areas */
movzwl 0x0e(%bp), %ebx /* reserved sectors */
Expand Down Expand Up @@ -2720,8 +2725,8 @@ Entry_exfat:
// movw %ax, %ds
// movw %ax, %es
movw %bp, %sp /* ss:sp=0000:7c00 */
pushl 0x8(%si) /* partition_table_entry.start_sector_ofs (LBA) */
sti
pushw %ax

movw %dx, 0x24(%bp) /* BIOS passes drive number in DL */

Expand All @@ -2733,10 +2738,12 @@ Entry_exfat:
movb $0x41, %ah
movw $0x55AA, %bx
int $0x13
popl %eax /* partition_table_entry.start_sector_ofs (LBA) */
jc 1f # No EBIOS
rorb %cl # ror cl: D0 C9
jnc 1f # No EBIOS
orb $0x80, 0x16(%bp) /* EBIOS supported */
movl %eax, 0x40(%bp) /* copy partition_table_entry.start_sector_ofs to hidden sectors */
jmp 2f
1:
movb $0x08, %ah
Expand All @@ -2745,6 +2752,7 @@ Entry_exfat:
andb $0x3f, %cl
movb %cl, 0x18(%bp)
2:
pushw %ss
popw %ds

movl 0x50(%bp), %eax
Expand Down Expand Up @@ -3244,7 +3252,7 @@ FAT_Address:
#define NT_FG_GPOS 8

#define nt_boot_drive -2(%bp)
#define nt_blocksize -4(%bp)
#define nt_blocksize 0xb(%bp)
#define nt_spc -5(%bp)
#define nt_mft_size -6(%bp)
#define nt_idx_size -7(%bp)
Expand Down Expand Up @@ -3325,7 +3333,8 @@ nt_part_ofs:
movw $0x7c00, %bp

movw %ax, %ss /* stack and BP-relative moves up, too */
leaw -0x20(%bp), %sp
leaw -0x20(%bp), %sp /* We need 0x20 bytes for the local variables nt_boot_drive etc. */
pushl 0x8(%si) /* partition_table_entry.start_sector_ofs (LBA) */
sti

movw %dx, nt_boot_drive
Expand All @@ -3338,6 +3347,7 @@ nt_part_ofs:
int $0x13

popw %ds /* DS=0 */
popl %eax /* partition_table_entry.start_sector_ofs (LBA) */

jc 1f /* No EBIOS */
cmpw $0xAA55, %bx
Expand All @@ -3348,6 +3358,7 @@ nt_part_ofs:
jnc 1f # No EBIOS
/* EBIOS supported */
movb $0x42, (ebios_nt - 1 - Entry_nt)(%bp)
movl %eax, 0x1c(%bp) /* copy partition_table_entry.start_sector_ofs to hidden sectors */
1:

pushw %ss /* SS=0 */
Expand All @@ -3364,9 +3375,7 @@ nt_part_ofs:
call readDisk_nt
1:

xorl %eax, %eax
movw 0xb(%bp), %ax // Bytes per sector (blocksize)
movw %ax, nt_blocksize
movzwl nt_blocksize, %eax // Bytes per sector (blocksize)

call convert_to_power_2
movb %cl, %bl
Expand Down Expand Up @@ -3538,6 +3547,8 @@ readDisk_nt:
pushw %bx /* buffer offset */
pushw $1 /* 1 sector to read */
pushw $16 /* size of this parameter block */
cmpb $0x42, (ebios_nt - 1 - Entry_nt)(%bp)
je 9f /* skip both of division by 0 below, avoiding crash caused by fatal interrupt */

xorl %ecx, %ecx
pushl 0x18(%bp) /* lo:sectors per track, hi:number of heads */
Expand All @@ -3558,6 +3569,7 @@ readDisk_nt:
shlb $6, %ah /* hi 2bit cylinder ... */
orb %ah, %cl /* ... should be in CL */

9:
movw $0x201, %ax /* read 1 sector */
ebios_nt: /* ebios_nt - 1 points to 0x02 that can be changed to 0x42 */

Expand Down Expand Up @@ -3594,15 +3606,6 @@ NTFS_Error:
jmp disk_error_nt


// Kernel load address, located at 0x1E8
// . = Entry_nt + 0x1e8

//nt_boot_image_end:

nt_loadseg_off:
.word 0
.word LOADSEG_NT

// Boot image offset and length, located at 0x1EE
// Lower 11 bit is offset, higher 5 bit is length
// . = Entry_nt + 0x1ec
Expand All @@ -3629,13 +3632,8 @@ print_ntfs:
int $0x10 /* via TTY mode */
cmpb $0, %al /* end of string? */
jne 1b /* until done */

/* The caller will change this to
* ljmp $0x9400, $(try_next_partition - _start1)
*/
jmp 1f

. = Entry_nt + 0x1e0
2:
jmp 2b

msg_NTFS_Not_Found_Error:
.ascii "No "
Expand All @@ -3646,18 +3644,16 @@ nt_boot_image:
msg_DiskReadError_nt:
.ascii "0\0"

. = Entry_nt + 0x1f4

error_go_back:
1:
jmp 1b

. = Entry_nt + 0x1fc

.word 0, 0xAA55

// Here starts sector #2

nt_loadseg_off:
.word 0
.word LOADSEG_NT

// Input:
// DI - current mft
ntfs_search:
Expand Down