* [Buildroot] [PATCH 1/1] arm: -march for Cortex A7, A12 and A15 is armv7ve @ 2014-09-28 1:10 Eddy Petrisor 2014-09-28 9:46 ` Yann E. MORIN 0 siblings, 1 reply; 3+ messages in thread From: Eddy Petrisor @ 2014-09-28 1:10 UTC (permalink / raw) To: buildroot From: Eddy Petri?or <eddy.petrisor@gmail.com> For Cortex A7, A12 and A15 setting -march=armv7-a will generate this type of warning by default: warning: switch -mcpu=cortex-a15 conflicts with -march=armv7-a switch This is because these cores have an instruction set which is based on the armv7-a set, but adds some extensions on top of them. This new set is called 'armv7ve' and is the default for A7, A12 and A15: http://gcc.gnu.org/viewcvs?rev=207237&root=gcc&view=rev With this patch we make sure we don't force the warning anymore. Signed-off-by: Eddy Petri?or <eddy.petrisor@gmail.com> --- arch/Config.in.arm | 6 +++--- toolchain/toolchain-external/Config.in | 6 +++--- 2 files changed, 6 insertions(+), 6 deletions(-) diff --git a/arch/Config.in.arm b/arch/Config.in.arm index 201ff1d..2988ac0 100644 --- a/arch/Config.in.arm +++ b/arch/Config.in.arm @@ -369,11 +369,11 @@ config BR2_GCC_TARGET_ARCH default "armv6zk" if BR2_arm1176jz_s default "armv6zk" if BR2_arm1176jzf_s default "armv7-a" if BR2_cortex_a5 - default "armv7-a" if BR2_cortex_a7 + default "armv7ve" if BR2_cortex_a7 default "armv7-a" if BR2_cortex_a8 default "armv7-a" if BR2_cortex_a9 - default "armv7-a" if BR2_cortex_a12 - default "armv7-a" if BR2_cortex_a15 + default "armv7ve" if BR2_cortex_a12 + default "armv7ve" if BR2_cortex_a15 default "armv4" if BR2_fa526 default "armv7-a" if BR2_pj4 default "armv4" if BR2_strongarm diff --git a/toolchain/toolchain-external/Config.in b/toolchain/toolchain-external/Config.in index 67ad450..a7b965b 100644 --- a/toolchain/toolchain-external/Config.in +++ b/toolchain/toolchain-external/Config.in @@ -9,7 +9,7 @@ comment "(e)glibc toolchains only available with shared lib support" config BR2_TOOLCHAIN_EXTERNAL_LINARO_ARM bool "Linaro ARM 2014.08" depends on BR2_arm - depends on BR2_GCC_TARGET_ARCH = "armv7-a" + depends on BR2_GCC_TARGET_ARCH = "armv7-a" || BR2_GCC_TARGET_ARCH = "armv7ve" depends on BR2_HOSTARCH = "x86_64" || BR2_HOSTARCH = "x86" depends on BR2_ARM_EABIHF depends on !BR2_PREFER_STATIC_LIB @@ -29,13 +29,13 @@ config BR2_TOOLCHAIN_EXTERNAL_LINARO_ARM comment "Linaro toolchains available for Cortex-A + EABIhf" depends on BR2_arm - depends on BR2_GCC_TARGET_ARCH != "armv7-a" || !BR2_ARM_EABIHF + depends on (BR2_GCC_TARGET_ARCH != "armv7-a" && BR2_GCC_TARGET_ARCH != "armv7ve") || !BR2_ARM_EABIHF depends on !BR2_PREFER_STATIC_LIB config BR2_TOOLCHAIN_EXTERNAL_LINARO_ARMEB bool "Linaro armeb 2014.08" depends on BR2_armeb - depends on BR2_GCC_TARGET_ARCH = "armv7-a" + depends on BR2_GCC_TARGET_ARCH = "armv7-a" || BR2_GCC_TARGET_ARCH = "armv7ve" depends on BR2_HOSTARCH = "x86_64" || BR2_HOSTARCH = "x86" depends on BR2_ARM_EABIHF depends on !BR2_PREFER_STATIC_LIB -- 1.9.2.459.g68773ac ^ permalink raw reply related [flat|nested] 3+ messages in thread
* [Buildroot] [PATCH 1/1] arm: -march for Cortex A7, A12 and A15 is armv7ve 2014-09-28 1:10 [Buildroot] [PATCH 1/1] arm: -march for Cortex A7, A12 and A15 is armv7ve Eddy Petrisor @ 2014-09-28 9:46 ` Yann E. MORIN [not found] ` <CAK0XTWcRzXZmst+zZ0VT=Jzb5P2qbFef3+0nP=jGvyo8qAUcHQ@mail.gmail.com> 0 siblings, 1 reply; 3+ messages in thread From: Yann E. MORIN @ 2014-09-28 9:46 UTC (permalink / raw) To: buildroot Eddy, All, On 2014-09-28 04:10 +0300, Eddy Petrisor spake thusly: > From: Eddy Petri?or <eddy.petrisor@gmail.com> > > For Cortex A7, A12 and A15 setting -march=armv7-a will generate this > type of warning by default: > > warning: switch -mcpu=cortex-a15 conflicts with -march=armv7-a switch > > This is because these cores have an instruction set which is based on > the armv7-a set, but adds some extensions on top of them. This new set > is called 'armv7ve' and is the default for A7, A12 and A15: > > http://gcc.gnu.org/viewcvs?rev=207237&root=gcc&view=rev > > With this patch we make sure we don't force the warning anymore. We have an on-going discussion about dropping -march altogether, and only keep the -mcpu option. But the situation is not quite simple. See the thread starting there: http://lists.busybox.net/pipermail/buildroot/2014-September/106214.html and especially the comments on patch 3 of that series: http://lists.busybox.net/pipermail/buildroot/2014-September/106218.html The status so far is: - some combinations of -march, -mcpu, -mtune are not valid, some are just a warning; - -mcpu is not always enough to fully specify the actual CPU; - gcc-5 will no longer accept some combinations of -march, -mcpu, -mtune (not sure exactly which will still be valid.) So, we'd like to go one of those routes (first is the preferred one): - drop -march and -mtune, only keep -mcpu; - conditionally set either (-mcpu) or (-march and -mtune) . So, there is a status-quo for now on this issue. I guess we'll be discussing this at the upcoming Developpers Days in D?sseldorf: http://elinux.org/Buildroot:DeveloperDaysELCE2014 Regards, Yann E. MORIN. > Signed-off-by: Eddy Petri?or <eddy.petrisor@gmail.com> > --- > arch/Config.in.arm | 6 +++--- > toolchain/toolchain-external/Config.in | 6 +++--- > 2 files changed, 6 insertions(+), 6 deletions(-) > > diff --git a/arch/Config.in.arm b/arch/Config.in.arm > index 201ff1d..2988ac0 100644 > --- a/arch/Config.in.arm > +++ b/arch/Config.in.arm > @@ -369,11 +369,11 @@ config BR2_GCC_TARGET_ARCH > default "armv6zk" if BR2_arm1176jz_s > default "armv6zk" if BR2_arm1176jzf_s > default "armv7-a" if BR2_cortex_a5 > - default "armv7-a" if BR2_cortex_a7 > + default "armv7ve" if BR2_cortex_a7 > default "armv7-a" if BR2_cortex_a8 > default "armv7-a" if BR2_cortex_a9 > - default "armv7-a" if BR2_cortex_a12 > - default "armv7-a" if BR2_cortex_a15 > + default "armv7ve" if BR2_cortex_a12 > + default "armv7ve" if BR2_cortex_a15 > default "armv4" if BR2_fa526 > default "armv7-a" if BR2_pj4 > default "armv4" if BR2_strongarm > diff --git a/toolchain/toolchain-external/Config.in b/toolchain/toolchain-external/Config.in > index 67ad450..a7b965b 100644 > --- a/toolchain/toolchain-external/Config.in > +++ b/toolchain/toolchain-external/Config.in > @@ -9,7 +9,7 @@ comment "(e)glibc toolchains only available with shared lib support" > config BR2_TOOLCHAIN_EXTERNAL_LINARO_ARM > bool "Linaro ARM 2014.08" > depends on BR2_arm > - depends on BR2_GCC_TARGET_ARCH = "armv7-a" > + depends on BR2_GCC_TARGET_ARCH = "armv7-a" || BR2_GCC_TARGET_ARCH = "armv7ve" > depends on BR2_HOSTARCH = "x86_64" || BR2_HOSTARCH = "x86" > depends on BR2_ARM_EABIHF > depends on !BR2_PREFER_STATIC_LIB > @@ -29,13 +29,13 @@ config BR2_TOOLCHAIN_EXTERNAL_LINARO_ARM > > comment "Linaro toolchains available for Cortex-A + EABIhf" > depends on BR2_arm > - depends on BR2_GCC_TARGET_ARCH != "armv7-a" || !BR2_ARM_EABIHF > + depends on (BR2_GCC_TARGET_ARCH != "armv7-a" && BR2_GCC_TARGET_ARCH != "armv7ve") || !BR2_ARM_EABIHF > depends on !BR2_PREFER_STATIC_LIB > > config BR2_TOOLCHAIN_EXTERNAL_LINARO_ARMEB > bool "Linaro armeb 2014.08" > depends on BR2_armeb > - depends on BR2_GCC_TARGET_ARCH = "armv7-a" > + depends on BR2_GCC_TARGET_ARCH = "armv7-a" || BR2_GCC_TARGET_ARCH = "armv7ve" > depends on BR2_HOSTARCH = "x86_64" || BR2_HOSTARCH = "x86" > depends on BR2_ARM_EABIHF > depends on !BR2_PREFER_STATIC_LIB > -- > 1.9.2.459.g68773ac > > _______________________________________________ > buildroot mailing list > buildroot at busybox.net > http://lists.busybox.net/mailman/listinfo/buildroot -- .-----------------.--------------------.------------------.--------------------. | Yann E. MORIN | Real-Time Embedded | /"\ ASCII RIBBON | Erics' conspiracy: | | +33 662 376 056 | Software Designer | \ / CAMPAIGN | ___ | | +33 223 225 172 `------------.-------: X AGAINST | \e/ There is no | | http://ymorin.is-a-geek.org/ | _/*\_ | / \ HTML MAIL | v conspiracy. | '------------------------------^-------^------------------^--------------------' ^ permalink raw reply [flat|nested] 3+ messages in thread
[parent not found: <CAK0XTWcRzXZmst+zZ0VT=Jzb5P2qbFef3+0nP=jGvyo8qAUcHQ@mail.gmail.com>]
* [Buildroot] [PATCH 1/1] arm: -march for Cortex A7, A12 and A15 is armv7ve [not found] ` <CAK0XTWcRzXZmst+zZ0VT=Jzb5P2qbFef3+0nP=jGvyo8qAUcHQ@mail.gmail.com> @ 2014-09-28 21:29 ` Yann E. MORIN 0 siblings, 0 replies; 3+ messages in thread From: Yann E. MORIN @ 2014-09-28 21:29 UTC (permalink / raw) To: buildroot Eddy, All, On 2014-09-28 23:53 +0300, Eddy Petri?or spake thusly: > Pe 28.09.2014 12:46, "Yann E. MORIN" <yann.morin.1998@free.fr> a scris: [--SNIP--] > > The status so far is: > > > > - some combinations of -march, -mcpu, -mtune are not valid, some are > > just a warning; > > This is why I wanted to fix this. The warning might seem harmless, but on > cortex a7, a12 and a15 the compilation of fontconfig fails since the test > for scandir uses -Werror. This means compiling Weston on these cpus is > impossible without a patch. > > Most likely this situation is true for other packages, so correcting the > default march might make things generally better for anyone developing now > for the armv7ve cores. > > That's why I would like this patch in, even if later it is decided march > and mtune are dropped or another fix is implemented. I am still not sure we want that patch in the current state, see below... > > - -mcpu is not always enough to fully specify the actual CPU; > > > > - gcc-5 will no longer accept some combinations of -march, -mcpu, -mtune > > (not sure exactly which will still be valid.) > > > > So, we'd like to go one of those routes (first is the preferred one): > > > > - drop -march and -mtune, only keep -mcpu; > > > > - conditionally set either (-mcpu) or (-march and -mtune) . > > > > So, there is a status-quo for now on this issue. I guess we'll be > > discussing this at the upcoming Developpers Days in D?sseldorf: > > http://elinux.org/Buildroot:DeveloperDaysELCE2014 > > I see. > > Would changing the default march as proposed in my patch break any > defconfig-s? The problem is tht armv7ve is a new thiung with gcc-4.9, and gcc-4.8 and below still consider those Cortex (plural: cortices?) as armv7-a. So, if we were to apply this patch, it would break: - for internal toolchains that use gcc 4.8 or below; we could fix it by conditionally setting -march to armv7-a or armv7-ve depending on the version of gcc being used for the toolchain; - for any external toolchain that use gcc-4.8 or below; for those, we have no way of knowing what gcc version is being used, so we can not ever set -march to armv7-ve. The only sane solution would be to drop -march altogether, which we are still pondering... One way I can foresee is: - drop -march in favour of just -mcpu, right now: makes all identified cases work, but a few CPUs may get non-optimized code (like those arm1136jf-s); - later re-introduce -mtune for those CPUs that require it. But this is touching core infra, and must be carefully analysed... Regards, Yann E. MORIN. -- .-----------------.--------------------.------------------.--------------------. | Yann E. MORIN | Real-Time Embedded | /"\ ASCII RIBBON | Erics' conspiracy: | | +33 662 376 056 | Software Designer | \ / CAMPAIGN | ___ | | +33 223 225 172 `------------.-------: X AGAINST | \e/ There is no | | http://ymorin.is-a-geek.org/ | _/*\_ | / \ HTML MAIL | v conspiracy. | '------------------------------^-------^------------------^--------------------' ^ permalink raw reply [flat|nested] 3+ messages in thread
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2014-09-28 1:10 [Buildroot] [PATCH 1/1] arm: -march for Cortex A7, A12 and A15 is armv7ve Eddy Petrisor
2014-09-28 9:46 ` Yann E. MORIN
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2014-09-28 21:29 ` Yann E. MORIN
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