[U-Boot] [PATCH v3 1/5] common: introduce maximum load size

[Wolfgang Denk]

Dear Rob,

In message <1397157488-8695-2-git-send-email-robherring2 at gmail.com> you wrote:
> 
> Various commands that load images have no checks that a loaded image
> does not exceed the available RAM space and will happily continue
> overwriting u-boot or other RAM that should not be touched. Also,
> some commands such as USB DFU or fastboot need to know the maximum
> buffer size, but there is no common way to define this.

You are mixing some pretty much unrelated things here, which is IMO
not a good idea.  Limiting the size for load operations is one thing,
but buffer size is something totally different.  These must not be
mixed up.  Please keep in mind that there is (or at least should be)
no need to load the whole file into a buffer. [Limitations of the
implementation should be fixed rather than supported.]

> Introduce a global load_size and environment variable loadsize to
> specify the size. The default is ~0UL which is effectively unlimited.

I think this feature should be made optional.  I don;t think I want to
have this on all systems.

> +  loadsize	- Maximum load size for commands like "bootp",
> +		  "rarpboot", "tftpboot", "loadb" or "diskboot"

Um... what makes these operations different from any other operations
that read images or other data to memory?  Like loading from NOR or
NAND flash, from USB, IDE or SATA storage devices, from any of the
supported file system types?

I feel we should either support this consequently everywhere, or not
at all.  My personal preference is the second option, as otherwise you
will just add a lot of code in too many places for too little benefit.

Best regards,

Wolfgang Denk

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