How do I download now
Chris Caudle
chris at chriscaudle.org
Tue Dec 30 21:58:51 UTC 2003
On Tue December 23 2003 6:34 am, Chris Sparks wrote:
> I would like to use my Disk On Chip to load my RTEMS application or even
> use it for my loader.
Not a problem.
You still need GrUB on a floppy to get started. There are other ways, but
that will be the easiest.
Go to the GrUB web page, and check the documentation, you will need to be
familiar with some commands for installing the first part of GrUB onto the
master boot record (the first sector).
http://www.gnu.org/software/grub/grub.html
> Since I am using the PC 686 BSP I would like to know more of how the
> BIOS knows where to go to boot from.
There are two steps involved. The first is figuring out which devices can
be accessed as block devices. For devices on the motherboard, that support
is typically included in the BIOS ROM of the motherboard.
For added devices, there are a set of defined addresses where cards can
provide their own support routines to be accessed from BIOS (known as the
Option ROM).
For block devices, like hard drives, the option ROM provides a service
routine for interrupt 13, which is a software interrupt used by the BIOS
for block access. I forget the details, but from what I remember you can
think of it as a wrapper around an IDE programmed I/O style interface.
Disk-On-Chip modules provide an option ROM which contains a driver for
accessing the Flash ROM within the D-O-C as a block device. The driver
also has additional features, like sector remapping with write wear
levelling, I think bad sector remapping is handled by the driver, etc.
That means that if you use D-O-C for more than just boot, you need the
driver compiled into your application.
CompactFlash is typically connected to an IDE style controller, so I think
you shouldn't notice any difference between CF and a real hard drive.
To get GrUB onto either, you follow the instructions in the GrUB
documentation for installing GrUB onto a hard drive. That typically
involves booting a floppy (or some other media with GrUB on it, such as an
extra hard drive that you have already installed GrUB on), and issuing
commands at the GrUB command prompt to copy the boot sector from the media
you just booted onto the new media.
I think you also need to copy some additional files to the device. The
details are covered in the documentation.
http://www.gnu.org/software/grub/manual/html_mono/grub.html#Installation
hope that helps,
Chris Caudle
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