[syslinux] [PATCH] core: Fix 'trackbuf' descriptor list byte length

[Ahmed S. Darwish]

(Tested using a Linux bzImage, with and without an initrd.)

Per shuffle_and_boot documentation, %ecx must contain the descriptor
list byte length, but it's set with such list end address instead.  Fix.

Signed-off-by: Ahmed S. Darwish <darwish.07 at gmail.com>
--

  core/bcopy32.inc   |    2 ++
  core/bcopyxx.inc   |    2 ++
  core/bootsect.inc  |    8 +++++---
  core/runkernel.inc |    2 +-
  4 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/core/bcopy32.inc b/core/bcopy32.inc
index 6537546..ab60145 100644
--- a/core/bcopy32.inc
+++ b/core/bcopy32.inc
@@ -65,6 +65,8 @@ bcopy:		jecxz .ret
 ;     If len == 0:  this marks the end of the list; dst indicates
 ;		    the entry point and src the mode (0 = pm, 1 = rm)
 ;
+;     (*) dst, src, and len are four bytes each
+;
 shuffle_and_boot_raw:
 		mov bx,pm_shuffle
 		jmp enter_pm
diff --git a/core/bcopyxx.inc b/core/bcopyxx.inc
index c669b7a..cfdda0b 100644
--- a/core/bcopyxx.inc
+++ b/core/bcopyxx.inc
@@ -205,6 +205,8 @@ pm_bcopy:
 ;     If len == 0:  this marks the end of the list; dst indicates
 ;		    the entry point and src the mode (0 = pm, 1 = rm)
 ;
+;     (*) dst, src, and len are four bytes each
+;
 pm_shuffle:
 		cli			; End interrupt service (for good)
 		mov ebx,edi		; EBX <- descriptor list
diff --git a/core/bootsect.inc b/core/bootsect.inc
index b4402f1..6c20409 100644
--- a/core/bootsect.inc
+++ b/core/bootsect.inc
@@ -169,7 +169,7 @@ replace_bootstrap_noclearmode:
 		mov [es:di+8],ax	; New DI
 		mov [es:di+4],bx	; New ES
 %endif
-		pop ax			; List length
+		pop ax			; descriptor list entries count
 
 		push di
 		push es
@@ -179,8 +179,8 @@ replace_bootstrap_noclearmode:
 
 		mov ebx,trackbuf
 		imul di,ax,12
+		push di			; length of list
 		add di,bx		; DI <- end of list
-		push di
 
 		; Terminating entry...
 		lea eax,[replace_stub]	; Entrypoint
@@ -196,8 +196,10 @@ replace_bootstrap_noclearmode:
 		mov cx,__replacestub_dwords
 		rep movsd
 
+		; ECX <- final list length
 		xor ecx,ecx
-		pop cx			; ECX <- length of list
+		pop cx			; original length in bytes
+		add cx, 12		; + termination entry size
 
 		pop word [replace_stub.ss]
 		pop word [replace_stub.esp]
diff --git a/core/runkernel.inc b/core/runkernel.inc
index 25b073f..2e94346 100644
--- a/core/runkernel.inc
+++ b/core/runkernel.inc
@@ -453,7 +453,7 @@ setup_move:
 
 .no_initrd:
 		push dword run_linux_kernel
-		push cx				; Length of descriptor list
+		push cx				; descriptor list entries count

 		; BX points to the final real mode segment, and will be loaded
 		; into DS.

thanks,

-- 
Darwish
http://darwish.07.googlepages.com