Changeset 95387 in vbox

Timestamp:

Jun 27, 2022 11:47:22 AM (2 years ago)

Author:

vboxsync

Message:

ValKit/bs3kit: Workaround for the FDC thinking 180K and 160K images are single sided and making them impossible to load (BIOS returns misleading drive parameters, and even if adjusted for we end up with a garbled image seemingly because we've been 'skipping' a side). bugref:9898

Location:

trunk/src/VBox/ValidationKit/bootsectors/bs3kit

Files:

• VBoxBs3Linker.cpp (modified) (2 diffs)
• bs3-bootsector.asm (modified) (7 diffs)

trunk/src/VBox/ValidationKit/bootsectors/bs3kit/VBoxBs3Linker.cpp

@@ -316 +316 @@
     free(paInputs);
 
+    /* Avoid output sizes that makes the FDC code think it's a single sided
+       floppy.  The BIOS always report double sided floppies, and even if we
+       the bootsector adjust it's bMaxHeads value when getting a 20h error
+       we end up with a garbaged image (seems somewhere in the BIOS/FDC it is
+       still treated as a double sided floppy and we get half the data we want and
+       with gaps). */
+    uint32_t cbOutput = ftell(pOutput);
+    if (   cbOutput == 512 * 8 * 40 /* 160kB 5"1/4 */
+        || cbOutput == 512 * 9 * 40 /* 180kB 5"1/4 */)
+    {
+        static uint8_t const s_abZeroSector[512] = { 0 };
+        if (fwrite(s_abZeroSector, sizeof(uint8_t), sizeof(s_abZeroSector), pOutput) != sizeof(s_abZeroSector))
+        {
+            fprintf(stderr, "error: fwrite failed (padding)\n");
+            rcExit = 1;
+        }
+    }
+
     /* Finally, close the output file (can fail because of buffered data). */
-    if (fclose(stderr) != 0)
+    if (fclose(pOutput) != 0)
     {
         fprintf(stderr, "error: Error closing '%s'.\n", pszOutput);
@@ -323 +341 @@
     }
 
-    fclose(pOutput);
+    fclose(stderr);
     return rcExit;
 }

trunk/src/VBox/ValidationKit/bootsectors/bs3kit/bs3-bootsector.asm

@@ -45 +45 @@
 ;; Enabled load progress dots.
 %define BS3KIT_BOOTSECTOR_LOAD_DOTS
+
+;; Halts on failure location. For debugging.
+;%define HLT_ON_FAILURE 1
 
 
@@ -252 +255 @@
 %if 0
         mov     al, '='
-        call    NAME(bs3PrintChrInAl)
+        call    bs3PrintChrInAl
 %endif
 
@@ -319 +322 @@
         mov     ah, 08h
         int     13h
+%ifndef HLT_ON_FAILURE
         jc      .failure
+%else
+        jnc     .ok_geometry_call
+        cli
+        hlt
+.ok_geometry_call:
+%endif
         and     cl, 63                  ; only the sector count.
         mov     bMaxSector, cl
@@ -376 +386 @@
         mov     ax, 0201h               ; al=1 sector; ah=read function
         int     13h
+%ifndef HLT_ON_FAILURE
         jc      .failure
+%else
+        jnc     .read_ok
+        cli
+        hlt
+.read_ok:
+%endif
 
         ; advance to the next sector/head/cylinder.
@@ -442 +459 @@
 
         cmp     ah, 9                   ; DMA 64KB crossing error
+%if 0 ; This hack doesn't work. If the FDC is in single sided mode we end up with a garbled image. Probably "missing" sides.
+        je      .read_one
+
+        cmp     ah, 20h                 ; Controller error, probably because we're reading side 1 on a single sided floppy
         jne     .failure
+        cmp     bMaxHead, 0
+        je      .failure
+        cmp     dh, 1
+        jne     .failure
+        xor     dh, dh
+        mov     bMaxHead, dh
+        inc     ch
+        jmp     .the_load_loop
+.read_one
+%else
+        jne     .failure
+%endif
         mov     ax, 1                   ; Retry reading a single sector.
-        jmp .read_again
+        jmp     .read_again
 
         ; advance to the next sector/head/cylinder and address.
@@ -486 +519 @@
         ret
 
+%ifndef HLT_ON_FAILURE
         ;
         ; Something went wrong, display a message.
         ;
 .failure:
-%if 1 ; Disable to save space for debugging.
+ %if 1 ; Disable to save space for debugging.
+  %if 1
         push    ax
+  %endif
 
         ; print message
@@ -502 +538 @@
 
         ; panic
+  %if 1
         pop     ax
- %if 1
         mov     al, ah
         push    bs3PrintHexInAl
- %endif
+  %endif
         call    Bs3Panic
 .s_szErrMsg:
         db 13, 10, 'rd err! '
-%else
+ %else
         hlt
         jmp .failure
+ %endif
 %endif
 .s_szErrMsgEnd: