[systemd-devel] [PATCH 2/5] udev.pc: install to pkgconfiglibdir

[Marc-Antoine Perennou]

On 8 April 2015 at 19:46, Kay Sievers <kay at vrfy.org> wrote:
> On Wed, Apr 8, 2015 at 7:34 PM, Marc-Antoine Perennou
> <Marc-Antoine at perennou.com> wrote:
>> On 8 April 2015 at 18:47, Kay Sievers <kay at vrfy.org> wrote:
>>> On Tue, Apr 7, 2015 at 8:54 PM, Marc-Antoine Perennou
>>> <Marc-Antoine at perennou.com> wrote:
>>>> ---
>>>>  Makefile.am | 3 +--
>>>>  1 file changed, 1 insertion(+), 2 deletions(-)
>>>>
>>>> diff --git a/Makefile.am b/Makefile.am
>>>> index 9fa4223..9b769ee 100644
>>>> --- a/Makefile.am
>>>> +++ b/Makefile.am
>>>> @@ -3725,8 +3725,7 @@ udevconfdir = $(sysconfdir)/udev
>>>>  dist_udevconf_DATA = \
>>>>         src/udev/udev.conf
>>>>
>>>> -sharepkgconfigdir = $(datadir)/pkgconfig
>>>> -sharepkgconfig_DATA = \
>>>> +pkgconfiglib_DATA += \
>>>>         src/udev/udev.pc
>>>
>>> This is all backwards. The systemd.pc file is also in the wrong location.
>>>
>>> These GENERIC files are supposed to be found by the primary AND the
>>> secondary arch at the same time, at the GENERIC location, not in a
>>> arch-specific libdir.
>>>
>>> How would the 32bit build find this file on a 64bit compat-arch/multilib system?
>>>
>>> Kay
>>
>> Well, let's imagine a full cross-compilation toolchain, with
>> CHOST-prefixed tools.
>>
>> x86_64 stuff will get built with x86_64-pc-linux-gnu-gcc
>> i686 stuff will get built with i686-pc-linux-gnu-gcc
>> (and you could add a lot of non-native archs here like arm, mips & co)
>>
>> x86_64-pc-linux-gnu-pkg-config will look into /usr/lib64/pkgconfig and
>> /usr/share/pkgconfig
>> i686-pc-linux-gnu-pkg-config will look into /usr/lib32/pkgconfig and
>> /usr/share/pkgconfig
>>
>> You says that systemd is in the wrong location, so let's see what's
>> going on with its
>> current location, and then if we move it to /usr/share
>>
>> Current location, libdir/pkgconfig/systemd.pc
>>
>> x86_64-pc-linux-gnu-pkg-config finds /usr/lib64/pkgconfig/systemd.pc containing,
>> amongst other things, libdir which is arch specific, /usr/lib64 and
>> systemdutildir
>> which contains arch-specific binaries (yes, /usr/lib64/systemd/systemd *is* an
>> ELF64 binary using an x86_64 interpreter.
>>
>> i686-pc-linux-gnu-pkg-config finds /usr/lib32/pkgconfig/systemd.pc (since it has
>> been cross-compiled too) and is pretty happy with that.
>>
>> arm-whatever-pkg-config finds /usr/arm-whatever/lib/systemd.pc and is
>> happy with it.
>>
>> If you move it to /usr/share/pkgconfig
>>
>> x86_64-pc-linux-gnu-pkg-config finds /usr/share/pkgconfig/systemd.pc
>> and is happy with it
>>
>> i686-pc-linux-gnu-pkg-config finds /usr/share/pkgconfig/systemd.pc and
>> tries linking to
>> x86_64 libraries
>>
>> arm-whatever-pkg-config finds /usr/share/pkgconfig/systemd.pc and
>> tries linking to
>> x86_64 libraries + it gets the path towards binaries its target won't
>> even be able to execute.
>>
>>
>> Hope that helps understanding the rational of putting pkgconfig files
>> pointing to
>> arch-specific libs/bins into an arch-specific place.
>>
>>
>> A good example of a pkgconfig file that is ok to install into
>> /usr/share/pkgconfig is
>> xorg-macros.pc which only leads to arch-independants macros.
>
> The point is, the purpose of that file is not cross-compiling. It is
> meant to provide information for the i686 toolchain which is nativly
> compiled on a x86_64 primary host.
>
> How is the i686 tool supposed to find the primary values of the
> installed native x86_64 tools if things are moved like you propose?
>

Why would it need to?

> The entire idea of adding $libdir to a file that is installed in
> $libdir to point to itself makes no sense at all, but that was the
> reason it was moved in the first place.
>
> Kay

Agreed about the redundancy, but what if the arm tool wants to find
installed arm tools, and not x86_64?