Re: [Qemu-devel] [RFC] configure script mistakenly detects static libraries

[Peter Maydell]

On 23 April 2018 at 17:10, Murilo Opsfelder Araujo
<address@hidden> wrote:
> Hi, everyone!
>
> I'm facing an issue on how configure script detects static libraries and
> would like to hear from community to find a common ground on how to
> possibly fix it.
>
> Throughout configure, we use pkg-config command to verify if a library
> is installed so qemu can be linked to it. This works fine when linking
> qemu dynamically. However, configuring qemu with --static can mistakenly
> detect a library that is actually not present on the system.
>
> For example, on Ubuntu Xenial, libcacard-dev package provides only
> libcacard.so (not libcacard.a) and pkg-config reports success in both
> cases:
>
>     $ pkg-config libcacard
>     $ echo $?
>     0
>
>     $ pkg-config --static libcacard
>     $ echo $?
>     0
>
> Since we use `pkg-config libcacard` to set smartcard=yes, this
> mistakenly enables smartcard feature. This is acceptable with dynamic
> linkage, but can be an issue with static linkage, where libcacard.a
> doesn't exist on the system, resulting on a build error:

This seems to me to be an error in your distro's pkg-config information.
If static linking against libcacard doesn't work, then
"pkg-config --static libcacard" should fail.

Unfortunately IME the static linking support in distro-suppled
pkgconfig files is rarely tested, so it's not uncommon for it to
be broken.

>From an upstream QEMU point of view, we primarily support --static
for the benefit of the linux-user binaries, not for system emulation.
So we care more if a "configure --disable-system --disable-tools --static"
build doesn't work, than if the problem is only with features used
by the system emulator binaries.

thanks
-- PMM