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-The Korat board has two NOR flashes, FLASH0 and FLASH1, which are connected to
-chip select 0 and 1, respectively. FLASH0 contains 16 MiB, and is mapped to
-addresses 0xFF000000 - 0xFFFFFFFF as U-Boot Flash Bank #2. FLASH1 contains
-from 16 to 128 MiB, and is mapped to 0xF?000000 - 0xF7FFFFFF as U-Boot Flash
-Bank #1 (with the starting address depending on the flash size detected at
-runtime). The write-enable pin on FLASH0 is disabled, so the contents of FLASH0
-cannot be modified in the field. This also prevents FLASH0 from executing
-commands to return chip information, so its configuration is hard-coded in
-U-Boot.
-
-There are two versions of U-Boot for Korat: "permanent" and "upgradable". The
-permanent U-Boot is pre-programmed at the top of FLASH0, e.g., at addresses
-0xFFFA0000 - 0xFFFFFFFF for the current 384 KiB size. The upgradable U-Boot is
-located 256 KiB from the top of FLASH1, e.g. at addresses 0xF7F6000 - 0xF7FC0000
-for the current 384 KiB size. FLASH1 addresses 0xF7FE0000 - 0xF7FF0000 are
-used for the U-Boot environmental parameters, and addresses 0xF7FC0000 -
-0xF7FDFFFF are used for the redundant copy of the parameters. These locations
-are used by both versions of U-Boot.
-
-On booting, the permanent U-Boot in FLASH0 begins executing. After performing
-minimal setup, it monitors the state of the board's Reset switch (GPIO47). If
-the switch is sensed as open before a timeout period, then U-Boot branches to
-address 0xF7FBFFFC. This causes the upgradable U-Boot to execute from the
-beginning. If the switch remains closed thoughout the timeout period, the
-permanent U-Boot activates the on-board buzzer until the switch is sensed as
-opened. It then continues to execute without branching to FLASH1. The effect
-of this is that normally the Korat board boots its upgradable U-Boot, but, if
-this has been corrupted, the user can boot the permanent U-Boot, which can then
-be used to erase and reload FLASH1 as needed.
-
-Note that it is not necessary for the permanent U-Boot to have all the latest
-features, but only that it have sufficient functionality (working "tftp",
-"erase", "cp.b", etc.) to repair FLASH1. Also, the permanent U-Boot makes no
-assumptions about the size of FLASH1 or the size of the upgradable U-Boot: it is
-sufficient that the upgradable U-Boot can be started by a branch to 0xF7FBFFFC.
-
-The build sequence:
-
- make korat_perm_config
- make all
-
-builds the permanent U-Boot by selecting loader file "u-boot.lds" and defining
-preprocessor symbol "CONFIG_KORAT_PERMANENT". The default build:
-
- make korat_config
- make all
-
-creates the upgradable U-Boot by selecting loader file "u-boot-F7FC.lds" and
-leaving preprocessor symbol "CONFIG_KORAT_PERMANENT" undefined.
-
-2008-02-22, Larry Johnson <lrj@acm.org>
-
-
-The CompactFlash(R) controller on the Korat board provides a hi-speed USB
-interface. This may be connected to either a dedicated port on the on-board
-USB controller, or to a USB port on the PowerPC 440EPx processor. The U-Boot
-environment variable "korat_usbcf" can be used to specify which of these two
-USB host ports is used for CompactFlash. The valid setting for the variable are
-the strings "pci" and "ppc". If the variable defined and set to "ppc", then the
-PowerPC USB port is used. In all other cases the on-board USB controller is
-used, but if "korat_usbcf" is defined but is set to a string other than the two
-valid options, a warning is also issued.
-
-2009-01-28, Larry Johnson <lrj@acm.org>