[U-Boot-Users] Compile-time flash dependencies

[Wolfgang Denk]

Dear Yuli,

in message <17061.20898.318765.498613 at astp0002.localdomain> you wrote:
> 
> But we're discussing only "environment in flash" case. All the rest is

Yes. I see no reason for a "but" in this sentence, though.

> unchanged. The CFG_ENV_SECT_SIZE is relevant for flash only, isn't it?

Yes. And the memory footprint  for  U-Boot  on  the  boot  device  is
essential.

> So look at the saveenv code (in common/env_flash.c). The following
> definition:
...
> allocates CFG_ENV_SECT_SIZE bytes on stack, in many cases this is
> 256KB. So we don't care for RAM data size but fight for every byte of
> code size? Anyway, nobody is forced to use new mechanism if and when I

Right. Normally U-Boot is used to boot an OS which  requires  several
megabytes  of  RAM  so  we  don't have to worry about allocating even
bigger temporary buffers in U-Boot.

> develop it. Also, I see no reason why U-Boot should be less convenient
> or less flexible than, say, PlanetCore.

I agree, if it can be avoided. But we have  clear  priorities.  Small
memory  footprint  is  much  hicher on the list than comparing U-Boot
against PlanetCore.

> Unrelated question, also regarding the environment. It looks like
> CFG_ENV_IS_EMBEDDED is unnecessary because ENV_IS_EMBEDDED is calculated
> and used. What do you think?

It was needed once, and I guess  nobody  ever  spent  the  effort  to
actually test all related platforms if it can be savely removed.

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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