[U-Boot-Users] [PATCH] Pass full u-boot environment to booting kernel

Wolfgang Denk
2004-09-15T13:24:20Z

In message <Pine.LNX.4.61.0409151456120.3838@mag.sysgo.com> you wrote:
>
> This argument seems to create a chicken-and-egg problem. Why don't you
> let people step ahead and implement this? FWIW, Pantelis's arguments

I also disagree with the solution itself. Passing the U-Boot
environment does not solve a couple of problems. IMHO bi_recs is a
much better way to implement this. I'm just waiting that there is
some form of agreement what to do.

All of this is not exactly new. This discussion has been going on for
more than two years now. Mark A. Greer made a nice proposal more than
2 years ago. See discussion on the linuxppc-embedded mailing list
that started as "EV-64260-BP & GT64260 bi_recs" around March 19,
2002. [Sorry, I'm aware that the lists and list archives are down;
please feel free to contact me if you want a copy of the relevant
postings.]

Then there has been the OCP work by Matt Porter - etc. etc.

There is a lot of good existing proposals, and it makes IMHO not much
sense to come up with yet another approach that does not solve the
old problems.

Regarding the use of the U-Boot environment - here is some of the
issues I see:

* there should be a way to pass information about "banks" of memory
(a list of entries with physical start address, size, type [RAM,
ROM, flash, ...], ...)

* There should be a list of network interface descriptions (MAC
address, IP address etc., speed and duplex capabilities and current
settings etc.)

And so on. bi_recs will allow to handle such lists very nicely.
Trying to do the same in the U-Boot environment would blow up the
environment and easily overflow it on most systems. Also parsing and
decoding the ASCII representation would slow down the Linux boot
process too much. Also the output of a "printenv" would become
unreadable, etc.

The longer you think about this, the more reasons you will find why
the U-boot environment is not an appropriate way to solve this
problem.

Best regards,

Wolfgang Denk

--
Software Engineering: Embedded and Realtime Systems, Embedded Linux
Phone: (+49)-8142-4596-87 Fax: (+49)-8142-4596-88 Email: wd at denx.de
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