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Re: [Qemu-devel] [RFC v7 12/16] configure: Use slow-path for atomic only
From: |
alvise rigo |
Subject: |
Re: [Qemu-devel] [RFC v7 12/16] configure: Use slow-path for atomic only when the softmmu is enabled |
Date: |
Mon, 7 Mar 2016 18:21:09 +0100 |
On Thu, Feb 18, 2016 at 5:40 PM, Alex Bennée <address@hidden> wrote:
>
> Alvise Rigo <address@hidden> 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?
I added this option in order to have a quick way to compile a binary
with an without backend, it has been useful in the development
process. Now it's probably time to drop it.
Thank you,
alvise
>
>>
>> Suggested-by: Jani Kokkonen <address@hidden>
>> Suggested-by: Claudio Fontana <address@hidden>
>> Signed-off-by: Alvise Rigo <address@hidden>
>> ---
>> 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
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