[U-Boot] Update and Cut down mach types

[Michael Schwingen]

Am 04/26/2011 11:38 PM, schrieb Reinhard Meyer:
>>
>>> So IMO, if we have mach-types in U-Boot for supporting Linux, then we
>>> should keep using a (reasonably) up-to-date Linux machine ID list just
>>> like we do now -- mach-types that disappear from the list mean Linux
>>> support has become useless for that machine in U-Boot. And if we have
>>> our own mach-type policy, different from "has linux support", then we
>>> need to specify what this policy is and how it is implemented.
>>
>> I think we should be gentle to users of existing code and avoid
>> breaking it. From now on, we could establish a policy that a mach-id
>> can only be referenced when and as long mainline Linux support for
>> this board exists.
>>
>> I'm open for suggestions.
>
>
> Hi Wolfgang, Albert,
>
> why don't we just create the #define MACH_xxx lines directly from the
> "http://www.arm.linux.org.uk/developer/machines/download.php". We don't
> need all the *_is_* macros in u-boot anyway. Then we would have just a
> few 1000
> lines of #define MACH_*
>
I had already proposed that - after all, that is the way Linux does it
as well: the mach-types.h file is auto-generated from that list (or now
from a cut-down version of that list), so directly using the original
list to generate the .h file in u-boot would completely cut out the
middle man.

This would have multiple advantages IMHO:

 - the downloaded file is terse: only one line per machine, compared
with the current mach-types.h where one added machine generates lots of
lines (most of which we do not need at all!). Reviewing a patch that
pulls in a new upstream version would be easier with the original file
instead of the .h file.

 - Newly added machines turn up much earlier. When bringing up a new
board, you will usually work on u-boot first. Having to wait until the
machine ID trickles down into the Linux kernel, and *then* gets pulled
into u-boot at some later time, makes for a substantial delay until
board patches can be submitted to u-boot.

- It would actually save space:
138803 Apr 27 12:12 mach-types   (freshly downloaded, complete
unfiltered list)
1177444 Apr  5 20:55 ./arch/arm/include/asm/mach-types.h  (from u-boot
master, before the patch that removes boards)

- There would be no problem with removing boards that are supported in
u-boot, but not in Linux mainline - we would have the IDs for all known
boards, while still saving space.

I do think the maintenance effort when using the original mach-types
file would be lower than with the current system. However, when I
proposed this before,

cu
Michael