From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yann E. MORIN Date: Fri, 18 Mar 2016 23:34:56 +0100 Subject: [Buildroot] [PATCH v2 02/17] arch/arm: Cortex-M3 provides only Thumb-2 In-Reply-To: <1458335299-27409-3-git-send-email-thomas.petazzoni@free-electrons.com> References: <1458335299-27409-1-git-send-email-thomas.petazzoni@free-electrons.com> <1458335299-27409-3-git-send-email-thomas.petazzoni@free-electrons.com> Message-ID: <20160318223456.GC32171@free.fr> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: buildroot@busybox.net Thomas, All, On 2016-03-18 22:08 +0100, Thomas Petazzoni spake thusly: > The Cortex-M cores only support Thumb-2, not Thumb. In fact, Thumb-2 > is a superset of Thumb, and we could have a single option for both in > Buildroot, since -mthumb on ARMv4/v5 means original Thumb, while > -mthumb on ARMv7 means Thumb 2. However, for clarity, it makes sense > to have two separate options. But in this case, Cortex-M3 should not > advertise that it supports Thumb, as in fact selecting Thumb would > generate Thumb-2 code. So, if a package has some assembly code written in Thumb not Thimb2, it should do sometinh like: ifeq ($(BR2_ARM_CPU_HAS_THUMB)$(BR2_ARM_CPU_HAS_THUMB2),y) FOO_OPTS += --enable-thumb endif whereas now it would only need to do: ifeq ($(BR2_ARM_CPU_HAS_THUMB)$(BR2_ARM_CPU_HAS_THUMB2),y) FOO_OPTS += --enable-thumb endif Right? > Signed-off-by: Thomas Petazzoni Reviewed-by: "Yann E. MORIN" Regards, Yann E. MORIN. > --- > arch/Config.in.arm | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/arch/Config.in.arm b/arch/Config.in.arm > index 33f763a..cd1ec33 100644 > --- a/arch/Config.in.arm > +++ b/arch/Config.in.arm > @@ -172,7 +172,6 @@ config BR2_cortex_a17 > select BR2_ARCH_HAS_MMU_OPTIONAL > config BR2_cortex_m3 > bool "cortex-M3" > - select BR2_ARM_CPU_HAS_THUMB > select BR2_ARM_CPU_HAS_THUMB2 > select BR2_ARM_CPU_ARMV7M > config BR2_fa526 > -- > 2.6.4 > > _______________________________________________ > 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. | '------------------------------^-------^------------------^--------------------'