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:
$ ./configure --target-list=ppc64-softmmu --static && make -j$(nproc)
[...]
/usr/bin/ld: cannot find -lcacard
A workaround can be specifying --disable-<feature> for all missing
libraries.
One possible solution would be having a function, e.g. check_pkg_config,
that writes a C skeleton and tries to compile it using the desired
library, given as function parameter. Thus, compile_prog would return
success if library actually exists on the system. For example:
check_pkg_config() {
local_pkg_name=$1
local_cflags=$($pkg_config --cflags $local_pkg_name)
local_ldflags=$($pkg_config --libs $local_pkg_name)
write_c_skeleton
compile_prog "$local_cflags" "$local_ldflags"
}
That would work for both dynamic and static linkages. Then we could just
replace `$pkg_config <package>` by `check_pkg_config <package>` in the
configure script.
My approach might not be the best and only one, so I'd like to hear from
you what would be a reasoanble solution to fix this situation.
Cheers
Murilo
