Message-Id: <200712022336.SAA12095@granite.sover.net>
To: linux-kernel@vger.kernel.org
Subject: PROBLEM: loadlin incompatible with 2.6.23 kernels
Date: 2007 12 02
Cc: lermen@elserv.ffm.fgan.de, lermen@fgan.de, davej@redhat.com,
       cebbert@redhat.com
reply-to: kmh@nerdshack.com
from: kmh@nerdshack.com (Kenneth Howlett)
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 4824
Lines: 93

The loadlin boot loader fails to boot 2.6.23 kernels.

I used msdos 6.22 in real mode, without himem.sys or any other memory
manager, without any tsrs; loadlin 1.6c; and kernel 2.6.23.1-42.fc8, which
is the install kernel for the fedora core 8 distribution. The normal loadlin
messages are displayed, the display is cleared and the cursor moves to the
upper left corner, and then nothing else happens. No kernel boot messages
are displayed. The computer does not respond to most keyboard actions, but
the computer does reboot when I press control-alternate-delete.

My computer is a dell dimension 4100 with pentium III 733mhz and intel
chipset, and ATI radeon all-in-wonder display controller.

The output of loadlin -d is:
LOADLIN v1.6c (C) 1994..2002 Hans Lermen <lermen@fgan.de>

Your current LINUX kernel boot configuration is:
  image file:       fed8.ker
  kernel version    2.6.23.1-42.fc8 (kojibuilder@xenbuilder1.fedora.redhat.com) #1 SMP Tue Oct 30 13:05:10 EDT 2007
  kernel size:     0x001E0300 (high loaded) setup size:  0x2C00, heap: 0x1200
  VGA mode:         0xFFFF
  command line (size 0x0013):
    BOOT_IMAGE=fed8.ker

Your current DOS/CPU configuration is:
  load buffer size: 0x00F60000 EXT , setup buffer size:  0x3E00
  lowmem buffer:    0x00080000 (part of load buffer)
  total memory:     0x040FFC00
  CPU is in REAL mode
  SetupIntercept: YES, legal intercept, setup header version 0206
  stat1: cpu in real 386 mode, no need to backswitch
  input params (size 0x0011):
    fed8.ker -d o.txt
  LOADLIN started from DOS-prompt

Option -t set, Linux not loaded


I tried using loadlin -f, and the result was the same. I tried using loadlin
-noheap, and the computer rebooted itself instead of crashing. I tried using
freedos 1.0 instead of msdos 6.22, and instead of crashing, the computer
displayed a message saying invalid opcode, and the dos prompt returned. I
tried using the 586, 686, and debug kernels from packages on the fedora core
8 dvd, and the result was the same. I tried using the pae kernel from the
package on the fedora core 8 dvd, and the computer crashed like before, but
this time the computer did not respond to control-alternate-delete.

Loadlin works ok with older kernels. The kernel works ok with other boot
loaders. I tested the integrity of my fedora core 8 dvd and it was ok.

I searched the web, and the only reference I found was
<a href="http://kerneltrap.org/node/14842">http://kerneltrap.org/node/14842</a>.
The first comment is from me. The person who wrote the original post
seems to be compiling his own kernels; therefore this is probably a kernel
problem, not a problem with the fedora core 8 distribution. The person who
wrote the original post says that kernel 2.6.22.12 did not have this
problem, therefore the problem probably appeared in the 2.6.23 kernels, and
earlier kernels are probably ok.

I do not know if the problem is with the kernel or with loadlin. Probably
some people will say it is the kernel's fault, and other people will say it
is loadlin's fault.

I am not knowledgable about the kernel boot process, but I am guessing that
the first thing the kernel does is uncompress itself, and the second thing
the kernel does is set the vga or framebuffer mode. I am guessing that the
clearing of the display is not done by loadlin, but is done as part of
setting the vga or framebuffer mode. Therefore I guessed that the kernel
successfully uncompressed itself, then got stuck setting the vga or
framebuffer mode. So I tried changing the vga options.

With vga=normal, the result is the same. With vga=771 (vesa framebuffer,
800x600, 256 colors), the computer crashes like before, but the cursor is
not visible in the upper left corner. With vga=ask, the computer displays a
message saying press enter for list, press space to continue. If I press
space, the computer crashes. If I press enter, the computer displays a list
of video modes. If I select 0, the computer crashes without changing the
display. If I select 1, the text becomes smaller and occupies a smaller part
of the display, and the computer crashes. If I select 2, the display
clears and the computer crashes. With all of these crashes, the computer can
still be rebooted by pressing control alternate delete.

I conclude that the problem occurs after or at the end of setting the vga or
framebuffer mode. The problem probably occurs before or at the beginning of
probing for hardware, because no kernel boot messages are displayed after
the vga=ask messages.

I do not know why this occurs with loadlin and not with other boot loaders.
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