[OE-core] [meta-clang] oe-core and meta-clang llvm coexsting?

[Martin Kelly]

On 03/31/2017 03:53 PM, Martin Kelly wrote:
> On 03/30/2017 04:58 PM, Martin Kelly wrote:
>> On 03/30/2017 12:31 PM, Khem Raj wrote:
>>>
>>>
>>> On 3/30/17 12:20 PM, Martin Kelly wrote:
>>>> Hi,
>>>>
>>>> I'm trying to integrate the meta-clang version of LLVM 4.0 (used for
>>>> recipes that need a newer LLVM version) alongside the oe-core
>>>> version of
>>>> LLVM 3.3 (used for mesa). I'd like some recipes to use LLVM 4.0 and
>>>> some
>>>> to use LLVM 3.3 and for them not to collide with each other.
>>>>
>>>> Right now, once the meta-clang layer is enabled, the recipes collide
>>>> because they both provide llvm-common.bb. I tried explicitly versioning
>>>> llvm-common, which makes them no longer collide. However, mesa then
>>>> fails to build because the meta-clang version of LLVM installs
>>>> llvm-config into the native common sysroot in
>>>
>>> merging all llvm-common into a single recipe might be good
>>
>
> I thought more about this issue. Absent some clever solution that allows
> us to unify the wrappers (which is difficult due to the issues I
> mentioned in the last mail), I think we have three routes that could
> work to at least allow meta-clang and meta-oe to exist in the same Yocto
> workspace without breakage:
>
> (a) Instead of installing llvm-config into
> ${SYSROOT_DESTDIR}${bindir_crossscripts} -- which causes collisions when
> meta-clang and meta-oe both try to overwrite the same shared file --
> install into ${D}{bindir}llvm-config, and install the binary llvm-config
> into ${D}${bindir}/llvm-config${PV}. Recipes requiring LLVM will then
> need to depend on either llvm-common3.3 or llvm-common4.0, but at least
> there will be no collision or ambiguity which one gets used.
>
> (b) Use a common wrapper in
> ${SYSROOT_DESTDIR}${bindir_crossscripts}/llvm-config that does what the
> meta-oe current version does; just exec
> ${SYSROOT_DESTDIR}${bindir_crossscripts}/llvm-config${WANT_LLVM_RELEASE}. Let
> the meta-oe LLVM 3.3 install the binary llvm-config into
> ${SYSROOT_DESTDIR}${bindir_crossscripts}/llvm-config3.3 and let the
> meta-clang LLVM 4.0 install its wrapper llvm-config into
> ${SYSROOT_DESTDIR}${bindir_crossscripts}/llvm-config4.0. meta-clang will
> have to use the second wrapper script because it needs to edit
> TARGET_CFLAGS and similar to avoid compiling target binaries using
> native flags (due to the CMake LLVM build which appears not to respect
> cross-compile).
>
> (c) Use a common llvm-config wrapper in
> ${SYSROOT_DESTDIR}${bindir_crossscripts}/llvm-config that does a
> hardcoded check for WANT_LLVM_RELEASE. If the version is 4.0 or greater,
> then edit the TARGET_CFLAGS and similar, otherwise don't.
>
> It seems to me that all these options are undesireable, but (a) is
> probably least so.
>
> Khem and others: which option would you like me to pursue, or do you
> have an alternate suggestion?
>

(friendly ping)