Changeset 141 for trunk/bootcode/airboot.asm

Timestamp:

Apr 8, 2017, 12:27:37 AM (8 years ago)

Author:

Ben Rietbroek

Message:

Moved the clearing of BSS variables to an earlier stage [v1.1.1-testing]

When debugging, we want 'AuxIO' available before 'PRECRAP'.

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

File:

• trunk/bootcode/airboot.asm (modified) (1 diff)

trunk/bootcode/airboot.asm

@@ -996 +996 @@
         pop     [OldSS]
 
+        ; Clear the BSS from its real start just upto the end of the variables.
+        ; Here 'real start' means from where the BSS begins, which is below
+        ; the point where the first variables are located. The part after
+        ; the variables is not cleared because that is where the old SS:SP is
+        ; stored, which is needed for AirBoot restarts during debugging.
+        mov     bx, offset sobss
+        mov     cx, offset EndOfVariables - offset sobss
+        xor     ax, ax
+        call    FillMemBlock
 
 ; Verify we still got the BIOS disk in DL