Hi,
On Tue, Jan 31, 2023 at 04:33:00PM +0100, Alexander Dahl wrote:
> I'm stuck with a problem where I can not find an elegant solution for.
> Let me describe.
>
> I have a layered BSP. The base layer has different platformconfigs for
> hardware targets with different SoC architectures, let's say the
> PTXCONF_PLATFORM is "pla" on one and "plb" on the other. (I can not build
> the
> whole stuff for one platform only, two platforms are strictly required.)
>
> There is a more or less ordinary CMake based target application in the base
> layer, let's say in "base/rules/myapp.{in,make}", because that application is
> needed on both platforms.
>
> The two upper layers select the different platforms with different toolchains
> and both also enable "myapp". (Yes, I could also have it all in a single
> layer BSP with two working copies and building one platform per working copy.
>
> Doesn't change the problem.)
>
> myapp depends on multiple libraries, some of them hardware specific. So for
> platform "pla" it needs "libmyliba" and for platform "plb" it does not.
>
> In "base/rules/myapp.make" I pass PTXCONF_PLATFORM as a build time option to
> CMake like this:
>
> MYAPP_CONF_OPT += -DHARDWARE_NAME=$(PTXCONF_PLATFORM)
>
> Depending on "HARDWARE_NAME" I call `find_package(myliba)` in
> "CMakeLists.txt"
> of myapp.
>
> I could do a "select LIBMYLIBA" in "base/rules/myapp.in" unconditionally, and
> that would make the build successful. In the BSP for platform "pla" CMake
> would look for libmyliba and link and on the target it would be used at
> runtime just fine. In the BSP for platform "plb" CMake would not look for
> it,
> would not complain, myapp would run happily on the target without using
> libmyliba just fine.
>
> However, libmyliba would be built for platform "plb" and it would be copied
> over to "plb" target and take space, but never be used there. Build time for
> it would be completely wasted. Even worse, user might find it on target and
> wonder what it means, although it's useless on platform "plb".
>
> I could _not_ add that "select LIBMYLIBA" and build would fail for target
> "pla" dependending on package build order. Also dependencies in opkg
> packages
> would not be correct then.
>
> What also does not work is this (in "base/rules/myapp.in"):
>
> select LIBMYLIBA if PLATFORM = "pla"
>
> This is valid syntax from Kconfig point of view, but PLATFORM is just not
> defined here at all. I assume configs/ptxconfig and configs/platform-pla/
> platformconfig are somewhat distinct Kconfig spaces and one can not simply
> reference to Kconfig options from the other side.
>
> Interestingly I can do `ptxdist print PTXCONF_PLATFORM` and `ptxdist print
> PTXCONF_MYAPP` and ptxdist prints variables from both Kconfig spaces. Also I
> can successfully use both in base/rules/myapp.make and that's at least
> somewhat misleading. (Misleading as in: Why can I use both here but not
> there?)
>
> That's where I'm stuck. Of course I looked through ptxdist git sources to
> find hints on how to solve this dilemma, but without luck.
>
> Would be happy if anyone could give a hint or suggest a solution.
You can add the dependency in just one layer:
Either copy myapp.in to rules/myapp.in in that layer and add the dependency
or (if that file is sufficiently complex), create rules/myapp.fixup.in
with:
-------------------------------------------
## SECTION=....
config MYAPP
select LIBMYLIBA
-------------------------------------------
Kconfig will basically just merge the two entries internally.
Then run "ptxdist oldconfig" in that layer. You'll get a modified ptxconfig
and a ptxconfig.diff with just PTXCONF_LIBMYLIBA=y (and comments).
You'll need to run oldconfig whenever the base ptxconfig changes. PTXdist
will complain if they are out of sync.
This is one of the use-cases I had in mind when I designed the layers in
PTXdist.
Michael
--
Pengutronix e.K. | |
Steuerwalder Str. 21 | http://www.pengutronix.de/ |
31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
