From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53913) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aWRd6-0006wn-AG for qemu-devel@nongnu.org; Thu, 18 Feb 2016 11:40:37 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aWRd2-0001Qo-1J for qemu-devel@nongnu.org; Thu, 18 Feb 2016 11:40:36 -0500 Received: from mail-wm0-x22f.google.com ([2a00:1450:400c:c09::22f]:38627) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aWRd1-0001Pw-8s for qemu-devel@nongnu.org; Thu, 18 Feb 2016 11:40:31 -0500 Received: by mail-wm0-x22f.google.com with SMTP id a4so33930822wme.1 for ; Thu, 18 Feb 2016 08:40:31 -0800 (PST) References: <1454059965-23402-1-git-send-email-a.rigo@virtualopensystems.com> <1454059965-23402-13-git-send-email-a.rigo@virtualopensystems.com> From: Alex =?utf-8?Q?Benn=C3=A9e?= In-reply-to: <1454059965-23402-13-git-send-email-a.rigo@virtualopensystems.com> Date: Thu, 18 Feb 2016 16:40:28 +0000 Message-ID: <871t8adlab.fsf@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Subject: Re: [Qemu-devel] [RFC v7 12/16] configure: Use slow-path for atomic only when the softmmu is enabled List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alvise Rigo Cc: mttcg@listserver.greensocs.com, claudio.fontana@huawei.com, qemu-devel@nongnu.org, pbonzini@redhat.com, jani.kokkonen@huawei.com, tech@virtualopensystems.com, rth@twiddle.net Alvise Rigo writes: > Use the new slow path for atomic instruction translation when the > softmmu is enabled. > > At the moment only arm and aarch64 use the new LL/SC backend. It is > possible to disable such backed with --disable-arm-llsc-backend. Do we want to disable the backend once it is merged? Does it serve a purpose other than to confuse the user? > > Suggested-by: Jani Kokkonen > Suggested-by: Claudio Fontana > Signed-off-by: Alvise Rigo > --- > configure | 14 ++++++++++++++ > 1 file changed, 14 insertions(+) > > diff --git a/configure b/configure > index 44ac9ab..915efcc 100755 > --- a/configure > +++ b/configure > @@ -294,6 +294,7 @@ solaris="no" > profiler="no" > cocoa="no" > softmmu="yes" > +arm_tcg_use_llsc="yes" > linux_user="no" > bsd_user="no" > aix="no" > @@ -880,6 +881,10 @@ for opt do > ;; > --disable-debug-tcg) debug_tcg="no" > ;; > + --enable-arm-llsc-backend) arm_tcg_use_llsc="yes" > + ;; > + --disable-arm-llsc-backend) arm_tcg_use_llsc="no" > + ;; > --enable-debug) > # Enable debugging options that aren't excessively noisy > debug_tcg="yes" > @@ -4751,6 +4756,7 @@ echo "host CPU $cpu" > echo "host big endian $bigendian" > echo "target list $target_list" > echo "tcg debug enabled $debug_tcg" > +echo "arm use llsc backend" $arm_tcg_use_llsc > echo "gprof enabled $gprof" > echo "sparse enabled $sparse" > echo "strip binaries $strip_opt" > @@ -4806,6 +4812,7 @@ echo "Install blobs $blobs" > echo "KVM support $kvm" > echo "RDMA support $rdma" > echo "TCG interpreter $tcg_interpreter" > +echo "use ld/st excl $softmmu" I think we can drop everything above here. > echo "fdt support $fdt" > echo "preadv support $preadv" > echo "fdatasync $fdatasync" > @@ -5863,6 +5870,13 @@ fi > echo "LDFLAGS+=$ldflags" >> $config_target_mak > echo "QEMU_CFLAGS+=$cflags" >> $config_target_mak > > +# Use tcg LL/SC tcg backend for exclusive instruction is arm/aarch64 > +# softmmus targets > +if test "$arm_tcg_use_llsc" = "yes" ; then > + if test "$target" = "arm-softmmu" ; then > + echo "CONFIG_ARM_USE_LDST_EXCL=y" >> $config_target_mak > + fi > +fi This isn't going to be just ARM specific and it will be progressively turned on for other arches. So perhaps with the CONFIG_SOFTMMU section: if test "$target_softmmu" = "yes" ; then echo "CONFIG_SOFTMMU=y" >> $config_target_mak # Use SoftMMU LL/SC primitives? case "$target_name" in arm | aarch64) echo "CONFIG_USE_LDST_EXCL=y" >> $config_target_mak ;; esac fi > done # for target in $targets > > if [ "$pixman" = "internal" ]; then -- Alex Bennée