Re: [RFC 0/6] Create central repository for boilerplate configuration

[Laszlo Ersek <lersek@redhat.com>]

On 09/20/17 23:09, Leif Lindholm wrote:
> On Wed, Sep 20, 2017 at 08:14:59PM +0200, Laszlo Ersek wrote:

>> (2) Replacing a build define called FOOBAR with CONFIG_FOOBAR will break
>> all downstream build scripts. Is the CONFIG_ prefix a requirement?
> 
> It was explicitly intended to break compatibility, to ensure we didn't
> end up with things accidentally working until something unrelated
> changed in the future.

Interesting idea. I guess we could try to reach out to all of the
"repeat builders" of OVMF.

> 
>> (3) I think PCDs should not be included in ConfigPkg DSC include files,
>> even if several platforms set the same value. The set of libraries and
>> driver modules commonly used for a given feature is mostly constant
>> across platforms (and it is easy to extend, incrementally); but I don't
>> think the same holds for PCDs. Especially if a user wants to change a
>> PCD for one platform but not the other. Even if repeated settings for a
>> PCD worked (all on the same level of "specificity"), I'd find the result
>> confusing.
> 
> Also a subject for discussion.
> My intent was that if most of the open source platforms had an
> override on the default of a particular Pcd, we could override it in
> the config fragments without changing the .dec (and affecting
> non-public ports).

Right, that's great...

> Individual platforms can still override (again).

... but this "again" part is what confuses me (assuming it would
technically work). We'd have a PCD default in the .dec, then a setting
in the central .dsc.inc that ultimately qualifies as a platform-level
setting, and finally a setting in the actual platform .dsc, which *also*
qualifies as a platform-level setting. IOW, one in the .dec, and two in
the (final) .dsc.

I have no clue if this works, but even if it does, the priority could
depend on the order of inclusion, which I find confusing.

Liming, Yonghong, can you guys please comment on this?

Thanks!
Laszlo