[U-Boot-Users] [PATCH] cfi_flash.c patches

[Wolfgang Denk]

In message <4309712D.1040301 at orkun.us> you wrote:
>
> Convenience is irrelevant. This flash is obviously designed with data
> protection as priority.

Convenience is not irrelevant. The existence of U-Boot itself is just
for convenience,

We don't care what the people who designed the flash had in mind.  In
U-Boot, the design is as follows:

* All flash is writable by default.

* Some parts of the flash may be  either  implictely  or  explicitely
  protected.

* Implicit protection: this covers those areas of the flash that  are
  used  to  store  data  that  are  required for correct operation of
  U-Boot and the hardware, i. e.

  - the U-Boot code and data
  - environment variables
  - any FPGA images etc. which are necessary for correct HW operation

* Explicit protection: arbitrary areas which have been  protected  by
  the user using the "protect" coommand.


Note:

* "protection" may or may  not  be  implemented  using  any  hardware
  protection mechanisms which may be available on some chips (and not
  be available on other types)

* In the current design there is *no* requirement that  any  explicit
  protection  settings  are  persistent,  i. e. it is perfectly legal
  (and actually the default, see above) that such settings  get  lost
  on  reboot, and that the board comes up from reset with unprotected
  flash


This design shall be implemented  by  all  boards  if  possible;  for
features  that  are  shared  across several boards like the cfi_flash
driver it is mandatory.


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
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