[syslinux] pxelinux bug's

[Iouri Kharon]

   Hi Geert!

Tuesday, June 19, 2007, you wrote:

>> The attached patch contains three small (although 2 of them are
>> fundamental :) fixes for pxelinux
GS> Peter prefers patches created with git.
Diff was created as -uP (old Linus style :). Ok, I'm recreate it with -up,
"not compress", and include inline :). But also attach is as text (included
attachment can't used for patch :).

Redescription:
1. Alignment error when more than one initramfs are loaded using initrd
   - the alignment of the last disk is discarded in calculations but is
   ALWAYS present when the loading procedure is called. As a result - the
   second image (cpio) is not recognized.

2. On some platforms (vmware for example :), READING from the video memory
   in the 32bit mode is impossible (causes an exeption). Taking in to account
   that the scroll function in ilinux/arch/i386/boot/compressed/misc.c
   works using a memcpy of the video memory, when the linux bootsector is given
   control and the cursor is at the end of the screen (-1-2 lines) an exception is
   arisen and in the presence of it's handler in the bootloader the system halts.
   Both lilo and grub handle this situation - the cursor is always somewhere at the
   middle of the screen when the control is given to the linux bootsector.
   When using pxelinux taking in to account that the PXE bios prints out the
   presence of the second initramfs which causes the screen to scroll and the bug
   to appear :)
   A very simple solution - the screen is cleared before giving control to the
   linux bootsector (in the patch).

3. If more than one initramfs are loaded then before every "Loading..."
   message (but the first) an extra new line is added. A small thingy but
   anyway :)

Best regards,
 Iouri                            mailto:bc-info at styx.cabel.net
-------------------------------------
--- syslinux-3.51/runkernel.inc.orig    2007-06-11 02:51:39.000000000 +0400
+++ syslinux-3.51/runkernel.inc 2007-06-19 12:19:37.000000000 +0400
@@ -472,6 +472,14 @@ kill_motor:
                 int 16h
 %endif
 ;
+; MUST clear screen before jmp to linux boot sector:
+; some configuration can't read videomemory and 'scroll' in misc.c don't work
+;
+                mov ax,0fh
+                int 10h
+                mov ax,3
+                int 10h
+;
 ; Set up segment registers and the Linux real-mode stack
 ; Note: es == the real mode segment
 ;
@@ -600,11 +608,8 @@ loadinitrd:
                mov es,ax
 
                push ecx                        ; Bytes to load
-               cmp dword [es:su_ramdisklen],0
-               je .nopadding                   ; Don't pad the last initrd
                add ecx,4095
                and cx,0F000h
-.nopadding:
                add [es:su_ramdisklen],ecx
                mov edx,[HighMemSize]           ; End of memory
                dec edx
@@ -626,6 +631,11 @@ loadinitrd:
                 mov edi,edx                    ; initrd load address
                push si
                mov si,crlfloading_msg          ; Write "Loading "
+               cmp ecx,[es:su_ramdisklen]
+               je .firstdisk
+               inc si                          ; Skip (doubling) CRLF on non first disk
+               inc si
+.firstdisk:
                call cwritestr
                 mov si,InitRDCName             ; Write ramdisk name
                 call cwritestr
  

-- 
Best regards,
 Iouri                          mailto:bc-info at styx.cabel.net
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