From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gustavo Zacarias Date: Wed, 17 Jul 2013 13:03:56 -0300 Subject: [Buildroot] [PATCH] arch/arm: add support for thumb(1) mode In-Reply-To: <20130717175838.2fc2831e@skate> References: <1374075555-9599-1-git-send-email-gustavo@zacarias.com.ar> <20130717175838.2fc2831e@skate> Message-ID: <51E6C06C.8070300@zacarias.com.ar> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: buildroot@busybox.net On 07/17/2013 12:58 PM, Thomas Petazzoni wrote: > I think this is misleading: Thumb doesn't allow to mix 16 bits and 32 > bits instructions like Thumb2 does. IIRC, with Thumb, a particular > function needs to be either completely Thumb (16 bits) or completely > ARM (32 bits), and there is the thumb-interworking mechanism between > the two. > > Which leads me to this question: is adding Thumb support as simple as > what you're adding? Aren't there some additional thumb-interworking > complexities to handle? http://infocenter.arm.com/help/topic/com.arm.doc.ihi0042e/IHI0042E_aapcs.pdf Section 5.6 is of interest, once OABI (APCS) was dropped interworking isn't that hard since it's mandatory for AAPCS. Regards.