[U-Boot] [PATCH] Kbuild: allow building tools without board configuration

[Tom Rini]

On Mon, Mar 31, 2014 at 03:24:19PM +0000, Alexey Brodkin wrote:
> Hi Tom,
> 
> On Mon, 2014-03-31 at 11:16 -0400, Tom Rini wrote:
> > On Mon, Mar 31, 2014 at 05:33:51PM +0900, Masahiro Yamada wrote:
> > 
> > > Prior to Kbuild, U-Boot could build under tools/ directory
> > > withour configuring for a specific board.
> > > 
> > > That feature was lost when switching to Kbuild.
> > > 
> > > This patch revives it again by adding a make target "tools-only".
> > > 
> > > Usage:
> > >   $ make tools-only
> > > 
> > > Neither board configuration nor cross compiler are required to
> > > build host tools.
> > > 
> > > Signed-off-by: Masahiro Yamada <yamada.m at jp.panasonic.com>
> > > Suggested-by: Alexey Brodkin <Alexey.Brodkin at synopsys.com>
> > > Cc: Alexey Brodkin <Alexey.Brodkin at synopsys.com>
> > > Cc: Simon Glass <sjg at chromium.org>
> > > Cc: Tom Rini <trini at ti.com>
> > 
> > Problem is that we make enabling the signature code (which adds more
> > deps on the host) based on the config, and this was intentional.   So
> > I'm not sure if we want to do this exactly, at least right now.
> 
> Could you please add a bit more clarifications for your comment.
> 
> I don't quite understand why do I need to have any info from a board
> configuration when building "mkimage" utility.
> 
> Maybe I'm missing something.
> 
> And the problem is without proposed patch it's virtually impossible (or
> I don't know how) to build "mkimage" without configuring the real board.
> 
> For example what Linux distros will do to build generic "mkimage" tool?

So, if you check out tools/mkimage.c you can see that if
CONFIG_FIT_SIGNATURE is set we add options for doing rsa/etc signatures
on parts of a FIT image (see doc/uImage.FIT/signature.txt).  But then
you need to have crypto libraries on the host available for linking.
When not set we capture the relevant flags and print out a message to
stderr.  Since generic distros today hate FIT images even more than
legacy images, I'm not overly concerned about that, today.

> 
> And I think it is very important to resolve before U-Boot v2014.04 gets
> released.

I agree, yes.

> 
> -Alexey 
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-- 
Tom
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