[U-Boot] [PATCH v2] Make FIT support really optional

[Thomas Petazzoni]

Carlos, Tom,

On Sat, 4 Jun 2016 14:39:22 -0300 (BRT), Carlos Santos wrote:

> > So, why?  I don't like the idea of making FIT support in mkimage
> > conditional.  
> 
> If FIT is not to be conditional then what's the purpose of the
> CONFIG_FIT_SIGNATURE configuration option? Looks like it exists
> exactly to make FIT support conditional, which seems to be a
> reasonable approach, since it helps to reduce the size of the boot
> loader.

CONFIG_FIT_SIGNATURE is I guess optional because it requires OpenSSL at
*build* time and the U-Boot developers don't want to force everyone to
have OpenSSL available to build U-Boot.

However, FIT support does not require any special build dependency, so
probably there's little interest from the U-Boot folks to make it
optional.

> > This makes the life of distribution people harder, not
> > easier.  The functions in common/bootm.c should be being discarded
> > in U-Boot itself when we don't have CONFIG_FIT_SIGNATURE.  Thanks!  
> 
> The patch exists because of "distribution people". I sent a patch to
> Buildroot[1] which was refused because it added dependencies on DTC
> and evolved to several follow-ups [2,3,4].

Right, *but* it is not because we make FIT support optional in
Buildroot that we have to make it optional in U-Boot.

We can perfectly have an option in Buildroot to enable/disable FIT
support which does *not* enable/disable FIT support in the U-Boot, but
only ensures that the relevant runtime dependencies (i.e DTC) are
enabled.

Of course, if the U-Boot developers want to make FIT support in the
bootloader itself an optional feature, why not, but it's clearly not a
requirement from our side.

Best regards,

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com