[ros-kernel]ReactOS Boot CD-ROM

[Eric K. <ek...@rz...>]

Hi!

We can now boot FreeLoader from a CD-ROM.

The bootsector uses the 'no emulation' mode and permits full access to the
CD-ROM, just like the WinNT boot CD. Because the cdfs driver is not able to
read files from a CD-ROM, we cannot boot ReactOS yet.

Some paths must be hardcoded into the bootsector (ISOBOOT.BIN) and
bootloader (aka FREELDR.SYS). Therefore I would like to suggest the
following directory structure for ReactOS CDs:

\REACTOS:
Location for all kernel-mode components (ntoskrnl, hal, drivers,
configuration files) that are used for booting. I don't think we need
architecture-specific directories (i386, alpha, ppc, mips, ia64, etc.)
because one CD should support only one architecture.

\REACTOS\SYSTEM32:
Location for user-mode compoments (ntdll.dll and smss.sys) that are used for
booting. In this case smss.exe is the renamed text-mode installation program
usetup.exe.

\INSTALL:
Location for all packed installation files (.cab files?).

\ (Root directory):
Location for remaining files (autorun.inf, readme.txt, etc.)




HOW TO create a bootable ReactOS CD-ROM
---------------------------------------

I suggest you use a CD-RW rather than a CD-R because you can reuse the
former one. This is important when you want to participate in writing the
startup (FreeLoader.sys) and install (usetup.exe) code.

This description is based on a german NERO 5.0 and 5.5, so some terms might
not be translated properly. Other programs, like WinOnCD, should provide
similar functionality.

1.) Create a new 'disk'. If the disk wizard pops up, close it and choose
'CD-ROM (boot)' on the left side of the dialog.

2.) Click the 'boot options' tab, click 'Image file' and select
'isoboot.bin' from your 'freeldr/bootsect' directory. Then change the
emulation type to 'no emulation' and the 'number of boot sectors' to 4.
(Note: IMO, this is a bug because the sector size of a CD-ROM is 2048 bytes,
not 512 bytes. The number of bootsectors should be 1.)

3.) Click the 'create' button to close the dialog. A new browser window for
the CD-ROM opens.

4.) Create a new directory 'I386' in the CD-ROM browser window.

5.) Add the files FREELDR.SYS and I386 directory and add FREELDR.INI to the
root directory of the CD-ROM.

6.) Now you can save your settings.

7.) Write the CD-ROM.

When you boot the CD, you should see the well known FreeLoader boot menu.
The suggested directory structure and the instructions to create a bootable
CD differ a little due to the hardcoded paths in the bootsector and
bootloader.

I can provide a packed iso image if you don't dare to build your own CD.


Comments, ideas and suggestions are welcome!


Regards,
Eric Kohl