Changeset 33

Timestamp:

Jan 13, 2013, 8:58:15 AM (13 years ago)

Author:

Ben Rietbroek

Message:

Fixed Partition <-> LVM-info correlation [2011-11-20]

Fixes

o Start of partition now used to find LVM drive-letter for PRI part

Previously, the index of a primary partition in the partition-table
was used to find it's corresponding LVM-record. However, this does
not work when partition-pointers are cross-linked, i.e. a pointer
with a lower index pointing to a partition located above the one(s)
of subsequent pointers. The start of the partition is now used to
identify the corresponding LVM-info.

Note

This commit and all following commits upto and including the RC3
commit [2012-09-09] are delayed commits from a local repository.
Also, the RC (Release Candidate) naming of the corresponding commits
is a bit misleading. One would label a revision with RC when near to
a final release. Since many things have changed between RC1,RC2 & RC3,
these RC's should be interpreted as mile-stones.

WARNING!!

All commits upto and including the commit of [2012-05-13] contain
a severe bug!! Building from these sources and then disabling
the 'force LBA' feature while also using the drive-letter feature or
editing the label can destroy the MBR on all attached disks!!
DO NOT DISABLE 'FORCE LBA USAGE' WHEN BUILT FROM THE ABOVE COMMITS!!

File:

• trunk/BOOTCODE/REGULAR/PARTMAIN.ASM (modified) (3 diffs)

trunk/BOOTCODE/REGULAR/PARTMAIN.ASM

@@ -1348 +1348 @@
         mov     dh,al       ; Save PRI or LOG
 
-        ; Save for later use
+        ; Save PRI/LOG indicator for later use
         push    dx
 
@@ -1375 +1375 @@
         pop     si
 
-        ; Point BX to LVM 1st drive-letter
-        mov     bx,offset [LVMSector]
-        add     bx,LocLVM_VolumeLetter2
-
 
         ; Restore PRI/LOG partition indicator and index
@@ -1395 +1391 @@
         popa
 
-        ; Calculate index for driveletter of PRI partition
-        mov     ax,03ch     ; Length of LVM record ?
-        mul     dl          ; Multiply by index
-        add     bx,ax       ; Point to LVM-driveletter
-
 
     is_not_pri:
 
-        ;
-        ; At this point BX points to the drive-letter related to the
+
+        ;
+        ; At this stage the LVM-info sector has been loaded at [LVMSector].
+        ; From here we look for an LVM entry for the partition.
+        ; If one is found, based on it's LBA-start, it's driveletter is used
+        ; in case byte 25h is zero.
+        ;
+
+
+        ; Search for the partition in the LVM info.
+        ; If found, CY is set and SI points to LVM entry.
+        push    si
+        mov     dl,bptr [si+LocIPT_Drive]
+        mov     ax,[si+LocIPT_AbsoluteBegin+00h]
+        mov     dx,[si+LocIPT_AbsoluteBegin+02h]
+        mov     si,offset [LVMSector]
+        call    LVM_SearchForPartition
+        mov     bx,si   ; BX now points to LVM entry
+        mov     dx,0    ; Setup null driveletter
+        pop     si
+
+        ; Oops, no valid LVM record was used so we have a null driveletter.
+        jnc     null_lvm_dl
+
+        ;
+        ; At this point BX points to the LVM-entry related to the
         ; partition, whether it was a logical or a primary one.
-        ; We convert it ('C'=80h etc) and put it in DH for later use.
-        mov     dh,[bx]
+        ; We get the drive-letter and convert it ('C'=80h etc)
+        ; and put it in DH for later use.
+        ;
+        mov     dh,[bx+LocLVM_VolumeLetter]
         ; Don't convert if zero
         test    dh,dh