Emilio G. Cota <c...@braap.org> writes:
> For now only add it for ELF platforms, since we rely on the linker's
> --dynamic-list flag to pass a list of symbols to be exported to the
> executable. An alternative would be to use -rdynamic, but that would
> expose all of QEMU's objects to plugins.
>
> I have no experience with non-ELF systems but I suspect adding support
> for those should be pretty easy.
>
> Signed-off-by: Emilio G. Cota <c...@braap.org>
As far as the configure logic is concerned:
Reviewed-by: Alex Bennée <alex.ben...@linaro.org>
I'm not quite following what is so special about the dynamic-list
symbols compared to the rest of the symbols in the binary. when I do
readelf -s they are all specified as GLOBAL DEFAULT.
Perhaps this will become clearer to me once I get to the implementation
of the plugins later in the series?
> ---
> configure | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 51 insertions(+)
>
> diff --git a/configure b/configure
> index 03bf719ca7..78e86098e5 100755
> --- a/configure
> +++ b/configure
> @@ -30,6 +30,7 @@ TMPO="${TMPDIR1}/${TMPB}.o"
> TMPCXX="${TMPDIR1}/${TMPB}.cxx"
> TMPE="${TMPDIR1}/${TMPB}.exe"
> TMPMO="${TMPDIR1}/${TMPB}.mo"
> +TMPTXT="${TMPDIR1}/${TMPB}.txt"
>
> rm -f config.log
>
> @@ -477,6 +478,7 @@ libxml2=""
> docker="no"
> debug_mutex="no"
> libpmem=""
> +plugins="no"
>
> # cross compilers defaults, can be overridden with --cross-cc-ARCH
> cross_cc_aarch64="aarch64-linux-gnu-gcc"
> @@ -1443,6 +1445,10 @@ for opt do
> ;;
> --disable-libpmem) libpmem=no
> ;;
> + --enable-plugins) plugins="yes"
> + ;;
> + --disable-plugins) plugins="no"
> + ;;
> *)
> echo "ERROR: unknown option $opt"
> echo "Try '$0 --help' for more information"
> @@ -1633,6 +1639,8 @@ Advanced options (experts only):
> xen pv domain builder
> --enable-debug-stack-usage
> track the maximum stack usage of stacks created
> by qemu_alloc_stack
> + --enable-plugins
> + enable plugins via shared library loading
>
> Optional features, enabled with --enable-FEATURE and
> disabled with --disable-FEATURE, default is enabled if available:
> @@ -5204,6 +5212,42 @@ if compile_prog "" "" ; then
> atomic64=yes
> fi
>
> +#########################################
> +# See if --dynamic-list is supported by the linker
> +
> +cat > $TMPTXT <<EOF
> +{
> + foo;
> +};
> +EOF
> +
> +cat > $TMPC <<EOF
> +#include <stdio.h>
> +void foo(void);
> +
> +void foo(void)
> +{
> + printf("foo\n");
> +}
> +
> +int main(void)
> +{
> + foo();
> + return 0;
> +}
> +EOF
> +
> +if compile_prog "" "-Wl,--dynamic-list=$TMPTXT" ; then
> + ld_dynamic_list="yes"
> +else
> + if test "$plugins" = "yes" ; then
> + error_exit \
> + "Plugin support requires specifying a set of symbols that " \
> + "are exported to plugins. Unfortunately your linker doesn't " \
> + "support the flag (--dynamic-list) used for this purpose."
> + fi
> +fi
> +
> ########################################
> # See if 16-byte vector operations are supported.
> # Even without a vector unit the compiler may expand these.
> @@ -6091,6 +6135,7 @@ echo "VxHS block device $vxhs"
> echo "capstone $capstone"
> echo "docker $docker"
> echo "libpmem support $libpmem"
> +echo "plugin support $plugins"
>
> if test "$sdl_too_old" = "yes"; then
> echo "-> Your SDL version is too old - please upgrade to have SDL support"
> @@ -6849,6 +6894,12 @@ if test "$libpmem" = "yes" ; then
> echo "CONFIG_LIBPMEM=y" >> $config_host_mak
> fi
>
> +if test "$plugins" = "yes" ; then
> + echo "CONFIG_PLUGINS=y" >> $config_host_mak
> + LIBS="-ldl $LIBS"
> + LDFLAGS="-Wl,--dynamic-list=\$(SRC_PATH)/qemu-plugins.symbols $LDFLAGS"
> +fi
> +
> if test "$tcg_interpreter" = "yes"; then
> QEMU_INCLUDES="-iquote \$(SRC_PATH)/tcg/tci $QEMU_INCLUDES"
> elif test "$ARCH" = "sparc64" ; then
--
Alex Bennée
