Re: [ptxdist] [PATCH] trace-cmd: add missing host-swig dependency

[Michael Olbrich <m.olbrich@pengutronix.de>]

On Mon, Apr 27, 2015 at 11:23:17AM +0200, Alexander Aring wrote:
> Hi Michael,
> 
> On Mon, Apr 27, 2015 at 10:56:28AM +0200, Michael Olbrich wrote:
> > On Mon, Apr 20, 2015 at 09:48:45AM +0200, Alexander Aring wrote:
> > > This patch adds a missing host-swig dependency which is needed by
> > > trace-cmd to generate some python bindings. Without host-swig I get the
> > > following compile error:
> > 
> > I've changed this to just select HOST_SWIG. The others should not be
> > necessary. Can you confirm that it still works? Maybe you didn't run
> > 'oldconfig'?
> > 
> 
> I need to admit, I was not sure about to handle this. I learned that
> "select" is in Kconfig an evil statement for doing selection on config
> entries which has also others "select/depends on" statements. Maybe this
> is only if the selected statement has a "depends on" only or ptxdist can
> handle this.

Well, things are not quite that simple. It depends on the use-case. Using
'select' only works correctly, when the selected option does not depend on
anything with 'depends on'. I the kernel that is usually a problem, so
'select' is avoided. In ptxdist, the toplevel options usually don't have
any 'depends on' so we can use 'select' here.
There are some exceptions and they cause problems occasionally :-)

> A "depends on" doesn't work here because it's noprompt. Now I realized
> that when I try to add all HOST_SWIG dependencies then this doesn't work
> because select doesn't give any information about the order on which
> dependency should be compiled at first.
> 
> Anyway these thinking about that confused me and I would say that a
> simple "select HOST_SWIG" is enough than I will trust you. I tested it
> and after running 'oldconfig' it works, also fine with the dependencies
> like 'host-libpcre'.

We organize the options in PTXdist in a way, so that a simple select is
(usually) enough.

Michael

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