Changeset 119

Timestamp:

Apr 8, 2017, 12:27:18 AM (8 years ago)

Author:

Ben Rietbroek

Message:

Now locating Master LVM-sectors when scanning disks [v1.1.1-testing]

Note that if LVM is set to be ignored in the SETUP, checking for a
signature will not be done and thus no Master LVM sectors will be found.

CAUTION:
This is a testbuild !
AirBoot uses the BIOS to access disks and a small coding error can trash
partition tables or other vital disk structures. You are advised to make
backups of TRACK0 and EBRs before using this testbuild. More info at:
​https://rousseaux.github.io/netlabs.air-boot/pdf/AirBoot-v1.1.0-manual.pdf

Location:

trunk/bootcode

Files:

• airboot.asm (modified) (1 diff)
• regular/driveio.asm (modified) (2 diffs)
• regular/other.asm (modified) (1 diff)
• regular/partscan.asm (modified) (1 diff)

trunk/bootcode/airboot.asm

@@ -2383 +2383 @@
 LVM_Bytes                   dw      MaxDisks  dup(?)
 LVM_TotalSecs               dq      MaxDisks  dup(?)
+LVM_MasterSecs              dd      MaxDisks  dup(?)
                             ALIGN   16
 

trunk/bootcode/regular/driveio.asm

@@ -1000 +1000 @@
             call    AuxIO_Print
             pop     si
-            ;~ call    DEBUG_DumpRegisters
+            call    DEBUG_DumpRegisters
             ;~ call    AuxIO_DumpSector
             ;~ call    AuxIO_DumpParagraph
@@ -1016 +1016 @@
         pop     es
 
+        ; Because JCXZ is used, LBA sector 0 is never loaded and checked.
+        ; This is of course no problem since it is the MBR.
     DriveIO_LocateMasterLVMSector_next:
         clc                             ; Indicate Master LVM sector not found

trunk/bootcode/regular/other.asm

@@ -416 +416 @@
 
 
-IFDEF   AUX_DEBUG
-        IF 1
-        mov     dl, [BIOS_BootDisk]
-        ;~ mov     dl, 81h
-        call    DriveIO_LocateMasterLVMSector
-        call    DEBUG_DumpRegisters
-        mov     si, offset [TmpSector]
-        call    AuxIO_DumpSector
-        ENDIF
-ENDIF
-
         ; =======================================
         ; Checks for MBR Virii :) I love that job

trunk/bootcode/regular/partscan.asm

@@ -61 +61 @@
 
         push    dx
+
+; ================================================ [ Locate Master LVM Sector ]
+
+        ; Locate the Master LVM sector for this disk.
+        ; If one is found, BX:AX will hold its LBA address, otherwise zero.
+        ; Note that if LVM is set to be ignored in the SETUP, checking for a
+        ; signature will not be done and thus no Master LVM sector will be
+        ; found.
+        call    DriveIO_LocateMasterLVMSector
+
+        ; Put the LBA address in the BSS location for this disk
+        xor     bh, bh                          ; Zero upper part of index
+        mov     bl, dl                          ; Get BIOS drive-number
+        and     bl, 7fh                         ; Strip bit 7
+        shl     bx, 3                           ; Mult by 4 for DWORD
+        add     bx, offset [LVM_MasterSecs]     ; Add the base offset
+        mov     [bx+00h], ax                    ; Store LBA low
+        xor     ax, ax                          ; LBA high always zero
+        mov     [bx+02h], ax                    ; Store LBA high
+
+;!
+;! DEBUG_BLOCK
+;! Check stored Master LVM LBA address.
+;!
+IFDEF   AUX_DEBUG
+        IF 1
+        pushf
+        pusha
+            push    si
+            mov     si, offset $+5
+            jmp     @F
+            db      10,'[Master LVM Sector]',10,0
+            @@:
+            call    AuxIO_Print
+            pop     si
+            xor     bh, bh
+            mov     bl, dl
+            and     bl, 7fh
+            shl     bx, 3
+            add     bx, offset [LVM_MasterSecs]
+            mov     al, [bx]
+            mov     ah, dl
+            call    DEBUG_DumpRegisters
+        popa
+        popf
+        ENDIF
+ENDIF
+
+; ========================================================= [ Scan Partitions ]
+
         call    PARTSCAN_ScanDriveForPartitions
         pop     dx