Re: [Etherboot-developers] Q: device naming....

[Eric W B. <ebi...@ln...>]

ke...@us... (Ken Yap) writes:

> >Tenatively I have made the url:
> >
> >file:///floppy0
> >file:///disk0
> >
> >With a +- offset to find the start of the boot file.
> >
> >Which is fine.
> >
> >I am wondering if that naming convention is find of if I should
> >switch to something like:
> >
> >file:///fd0
> >file:///hd0
> 
> Any chance of booting from SCSI in future?

Definitely.

> Flash disks?
 
Compact flash already works with the IDE driver.  And I don't see a
problem with writing a driver for something like the DOC millenium.
The current infrastructure works on anything that has a random read
operation.

The really interesting piece will be getting the console code flexible
enough so it can have a flexible set of drivers as well.  Under
LinuxBIOS we need something like a framebuffer so we can enable the
video.

> Using an
> existing naming convention like Linux's has the advantage you have
> a ready made stock of names.

Matching up 100% is impossible on physical devices.  Linux can't
even do it from kernel to kernel.  And if the names don't match 100%
I'm not certain they should match at all.

What I am trying to do with the names is have a name for a class
of devices.  nics, hard drive, floppy drives, cds, tapes, dislpay.  An
average machine will normally have only one device of each class.  So
for a simple machine the names will be unambiguous, and predictable.
``file:///disk0'' will mean your first disk if it scsi, ide, or even
if it is plugged into the second channel of your ide controller
instead of the first.

On top of this infrastructure I also intend to have a setup of
bootorder where it selects which devices to boot from.

Having a seperate device class does not imply having a seperate
driver merely the probe() (descended from eth_probe) will look
for that device seperately from others.

> >And on the same subject I am wondering if the old disk code
> >that reads from the pcbios has enough merits to even be kept.
> 
> What does it do again? Only transfers control to the MBR IIRC?

Two pieces.
- try_floppy_first(), read from the floppy disk, and returns to
  the BIOS if it doesn't get an error.
- The second case bootdisk() transfers control to the MBR.

Eric