From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:55296) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aWRfX-0001qY-7K for qemu-devel@nongnu.org; Thu, 18 Feb 2016 11:43:08 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aWRfT-0002iF-3z for qemu-devel@nongnu.org; Thu, 18 Feb 2016 11:43:07 -0500 Received: from mail-wm0-x232.google.com ([2a00:1450:400c:c09::232]:38140) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aWRfS-0002hY-PW for qemu-devel@nongnu.org; Thu, 18 Feb 2016 11:43:03 -0500 Received: by mail-wm0-x232.google.com with SMTP id a4so34037669wme.1 for ; Thu, 18 Feb 2016 08:43:02 -0800 (PST) References: <1454059965-23402-1-git-send-email-a.rigo@virtualopensystems.com> <1454059965-23402-13-git-send-email-a.rigo@virtualopensystems.com> <871t8adlab.fsf@linaro.org> From: Alex =?utf-8?Q?Benn=C3=A9e?= In-reply-to: <871t8adlab.fsf@linaro.org> Date: Thu, 18 Feb 2016 16:43:00 +0000 Message-ID: <87ziuyc6ln.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 Alex Bennée writes: > 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? Also this needs to be after the actual implementation has been filled in or you'll have a broken build! > >> >> 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