[LinuxBIOS] booting XP

Stefan Reinauer stepan at coresystems.de
Tue Nov 7 11:58:07 CET 2006

* Segher Boessenkool <segher at kernel.crashing.org> [061107 10:16]:
> If you care about mswindows at all, it sure is.  

according to OSnews.com as well as
http://www.w3schools.com/browsers/browsers_stats.asp Windows has a
market share of about 90% in the PC market.

If LinuxBIOS is at all aiming at becoming an alternative firmware 
for PCs, really nobody would assume we can afford not to care.

Given that we can only keep up with supporting new server chipsets
if we have a user base worth mentioning, there is no way around
targeting the PC market as well.

> Does this work for vista too though?

We will need to find out by trying. There is no single future proof path
or optimal solution unfortunately. 

- The "16bit bios callback approach"

  Using ADLO or something similar will help for Windows Vista, but it
  would need work on the built-in IDE driver, plus it would need work to
  get int13 plugin cards working.

  The strength of this approach is that by using a 16bit legacy
  interface cleanly encapsulated, we might be able to boot from any
  PCI plugin card, such as SCSI adapters.

  The weakness is clearly that we need to stick with 16bit legacy code
  (which we already do for vga init anyways)

  It sounds somewhat weird that we need to go ancient to support 
  newer systems than what is there today, but this might indeed be the

- The patchwork approach

  We create clean 32bit loaders for the operating systems we want to
  boot. Or we modify or enhance existing loaders to do so.

  The strength of this approach is we might be able to use Linux for
  booting from flash, gaining from Linux' good driver support.

  The weakness of this approach is we need to reflash the BIOS if we
  plug in a new SCSI adapter because the old one died. All SCSI drivers
  in Linux require about 5MB space, 1.3 for all ide devices, 1.5 for
  Infiniband. Even with pretty good compression, how are we going to
  plug this, plus a kernel, plus a bootloader plus LinuxBIOS in 1MB

  Even though I am sure almost all people on this list compile their own
  kernels, this is not the usual case for people using Linux anymore.
  _Requiring_ to recompile your _BIOS_ to support booting from a new PCI 
  card will not make us a lot of friends.

So here we go. That's quite some of the misery along the mainstream
path. Solutions, anyone?

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