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authorH. Peter Anvin <hpa@zytor.com>2008-07-16 11:27:00 -0700
committerH. Peter Anvin <hpa@zytor.com>2008-07-16 11:28:02 -0700
commitced2310422003318c1c8bf22cabc7b444ee07bdc (patch)
treef366ddf62b8aa7ed0e5682bd297e7f5d01b75ebf /core
parent9e93f6b57fb74ff53b1cbdf3cfaff1e8b3642046 (diff)
downloadsyslinux-elf-ced2310422003318c1c8bf22cabc7b444ee07bdc.tar.gz
syslinux-elf-ced2310422003318c1c8bf22cabc7b444ee07bdc.tar.xz
syslinux-elf-ced2310422003318c1c8bf22cabc7b444ee07bdc.zip
adv: fix the handling of the ADV with CBIOS
Fix numerous problems in the way we handled the ADV with CBIOS. The EBIOS code was largely correct, but the CBIOS code was just busted. Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Diffstat (limited to 'core')
-rw-r--r--core/adv.inc64
1 files changed, 39 insertions, 25 deletions
diff --git a/core/adv.inc b/core/adv.inc
index c5e8270c..1fe5aca2 100644
--- a/core/adv.inc
+++ b/core/adv.inc
@@ -341,25 +341,6 @@ adv_read_write:
mov [ADVOp],ah
pushad
- mov dl,[ADVDrive]
- and dl,dl
- ; Floppies: can't trust INT 13h 08h, we better know
- ; the geometry a priori, which means it better be our
- ; boot device. Handle that later.
- ; jns .floppy ; Floppy drive... urk
-
- mov ah,08h ; Get disk parameters
- int 13h
- jc .noparm
- and ah,ah
- jnz .noparm
- shr dx,8
- inc dx
- mov [ADVHeads],dx
- and cx,3fh
- mov [ADVSecPerTrack],cx
-
-.noparm:
; Check for EDD
mov bx,55AAh
mov ah,41h ; EDD existence query
@@ -367,6 +348,10 @@ adv_read_write:
int 13h
mov si,.cbios
jc .noedd
+ cmp bx,0AA55h
+ jne .noedd
+ test cl,1
+ jz .noedd
mov si,.ebios
.noedd:
@@ -422,8 +407,38 @@ adv_read_write:
push eax
push bp
- movzx esi,word [ADVSecPerTrack]
- movzx edi,word [ADVHeads]
+ mov dl,[ADVDrive]
+ and dl,dl
+ ; Floppies: can't trust INT 13h 08h, we better know
+ ; the geometry a priori, which means it better be our
+ ; boot device...
+ jns .noparm ; Floppy drive... urk
+
+ mov ah,08h ; Get disk parameters
+ int 13h
+ jc .noparm
+ and ah,ah
+ jnz .noparm
+ shr dx,8
+ inc dx
+ movzx edi,dx ; EDI = heads
+ and cx,3fh
+ movzx esi,cx ; ESI = sectors/track
+ jmp .parmok
+
+.noparm:
+ ; No CHS info... this better be our boot drive, then
+%if IS_SYSLINUX || IS_EXTLINUX
+ cmp dl,[DriveNumber]
+ jne .cb_overflow ; Fatal error!
+ movzx esi,word [bsSecPerTrack]
+ movzx edi,word [bsHeads]
+%else
+ ; Not a disk-based derivative... there is no hope
+ jmp .cb_overflow
+%endif
+
+.parmok:
;
; Dividing by sectors to get (track,sector): we may have
; up to 2^18 tracks, so we need to use 32-bit arithmetric.
@@ -453,7 +468,7 @@ adv_read_write:
mov ch,al
mov dh,dl
mov dl,[ADVDrive]
- xchg ax,bp ; Sector to transfer count
+ mov al,01h ; Transfer one sector
mov ah,[ADVOp] ; Operation
mov bp,adv_retries
@@ -467,6 +482,7 @@ adv_read_write:
pop bp
pop eax
pop edx
+ pop si
ret
.cb_error:
@@ -481,9 +497,7 @@ adv_read_write:
ADVSec0 dd 0 ; Not specified
ADVSec1 dd 0 ; Not specified
ADVDrive db -1 ; No ADV defined
+ADVCHSInfo db -1 ; We have CHS info for this drive
section .bss
- alignb 4
-ADVSecPerTrack resw 1
-ADVHeads resw 1
ADVOp resb 1