IA32/x86 x86-Based PC

Overview

RedBoot supports two serial ports and an Intel i82559 based ethernet card (for example an Intel EtherExpress Pro 10/100) for communication and downloads. The default serial port settings are 38400,8,N,1.

The following RedBoot configurations are supported:

Configuration	Mode	Description	File
Floppy	[Floppy]	RedBoot running from a boot floppy disk installed in the A: drive of the PC.	redboot_ROM.ecm

Initial Installation

RedBoot takes the form of a self-booting image that must be written onto a formatted floppy disk. The process will erase any file system or data that already exists on that disk, so proceed with caution.

For Red Hat Linux users, this can be done by:

$ dd conv=sync if=install/bin/redboot.bin of=/dev/fd0H1440

For NT Cygwin users, this can be done by first ensuring that the raw floppy device is mounted as /dev/fd0. To check if this is the case, type the command mount at the Cygwin bash prompt. If the floppy drive is already mounted, it will be listed as something similar to the following line:

  \\.\a: /dev/fd0 user binmode

If this line is not listed, then mount the floppy drive using the command:

$ mount -f -b //./a: /dev/fd0

To actually install the boot image on the floppy, use the command:

$ dd conv=sync if=install/bin/redboot.bin of=/dev/fd0

Insert this floppy in the A: drive of the PC to be used as a target and ensure that the BIOS is configured to boot from A: by default. On reset, the PC will boot from the floppy and be ready to be debugged via either serial line, or via the ethernet interface if it is installed.

NOTE: Unreliable floppy media may cause the write to silently fail. This can be determined if the RedBoot image does not correctly boot. In such cases, the floppy should be (unconditionally) reformatted using the fdformat command on Linux, or format a: /u on DOS/Windows.

Flash management

PC RedBoot does not support any FLASH commands.

Special RedBoot Commands

None.

Memory Maps

All selectors are initialized to map the entire 32-bit address space in the familiar protected mode flat model. Page translation is not used. RAM up to 640K is mapped to 0x0 to 0xa0000. RAM above 640K is mapped from address 0x100000 upwards. Space is reserved between 0xa0000 and 0x100000 for option ROMs and the BIOS.

Rebuilding RedBoot

These shell variables provide the platform-specific information needed for building RedBoot according to the procedure described in Chapter 3:

export TARGET=pc
export ARCH_DIR=i386
export PLATFORM_DIR=pc

The names of configuration files are listed above with the description of the associated modes.