[syslinux] Recovery console doesn't work in chain.c32 3.85 or 3.86-pre1

[Gert Hulselmans]

The Windows recovery console doesn't work with chain.c32 3.85 or 3.86-pre1.

COM32 chain.c32
APPEND cmldr=/cmldr

Initially reported by cdob at:
http://www.boot-land.net/forums/index.php?showtopic=10487#entry94001

It did work fine with the: "chain.c32: Handle nonlinear logical partitions"
patch.
The following patch broke the recovery console hack:
chain.c32: add option to set hidden sectors; load boot sector for NTLDR
http://git.kernel.org/?p=boot/syslinux/syslinux.git;a=commit;h=033fb123375ce6af905dcb2408fa0df74960e066

You can download a small image:
http://ubcd.stopspazzing.com/downloads/cmdcons.img.gz

You can test it in qemu:
$ qemu -boot c -hda cmdcons.img


syslinux.cfg file:
UI menu.c32



LABEL 1

MENU LABEL Recovery console (RC) original patch (working)

COM32 chain_g.c32

APPEND cmldr=/cmldr



LABEL 2

MENU LABEL Recovery console (for fixing chain.c32 3.86-pre1)

COM32 chain.c32

APPEND cmldr=/cmldr



LABEL 3

MENU LABEL Boot Grub4dos (grldr) like RC and display contents of 0000:7C03

COM32 chain.c32

APPEND cmldr=/grldr


When you boot grub4dos from the menu, you can read the memory address to
which the "cmdcons" string should be written:

For the 'Read contents at 0x7C03', grub4dos returns:
  Booting Read contents at 0x7C03

Address 0x7c03: Value 0xd08ed88e
Address 0x7c07: Value 0x897c00bc


- Gert Hulselmans