[U-Boot-Users] Flash configuration

[Wolfgang Denk]

In message <6DABE12DF62766479F2A94F7E3157C5F9B2890 at lisi053a.siemens.pt> you wrote:
> 
> 	I'm configuring u-boot (for the first time) so that i can have 2 flash
> eprom chips, in two different banks, for a mpc8272 based board. They are
> organized the following way:
> 	
> 		BOOT Flash -> starts at 0xFFF00000 and has 512KB of size. (read-only)
> 		Linux Flash -> starts at 0x50000000 and has 64MB of size. (CFI
> compatible)
> 
> 	Since CFG_FLASH_BASE is used throughout the u-boot code as a reference,
> which one should it be? The boot flash address or the linux flash
> address? I'm really confused here...

FLASH_BASE is closely related to the location of U-Boot in flash,  so
it has to be set to match the start address of your "boot flash".

> 	Should I use the cfi_flash driver, provided by u-boot? Or should I

This is mostly a mtter of taste, and how you design your system.

Some configurations handle the "boot flash" as  "ROM"  (your  use  of
"read  only"  above seems to indicate such intentions, too), and they
configure U-Boot such that it is not even included  in  the  "flinfo"
display and thus cannot be written by standard U-Boot commands.

Others expose all flash banks to the user, which is IMHO  the  better
approach - sooner or later you *will* want to update the U-Boot image
in  your  "boot  flash"  and you will execrate the idiot who disabled
write access to this chip. Probably rather sooner than  later.  Also,
the  boot  flash  is probably an excellent location to store U-Boot's
environment sectors without creating gaps or reserved areas  in  your
"Linux flash".

If you want to use the CFI driver or your own is also mostly a matter
of taste - and code size requirements.

Best regards,

Wolfgang Denk

-- 
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de