From mboxrd@z Thu Jan 1 00:00:00 1970 From: Siarhei Siamashka Date: Tue, 7 Mar 2017 03:02:05 +0200 Subject: [U-Boot] [PATCH 1/1] arm: Migrate SYS_THUMB_BUILD to Kconfig, introduce SPL_SYS_THUMB_BUILD In-Reply-To: <20170306225417.GM19897@bill-the-cat> References: <1488826210-3685-1-git-send-email-trini@konsulko.com> <20170307004459.047ecd08@i7> <20170306225417.GM19897@bill-the-cat> Message-ID: <20170307030205.34e9f731@i7> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On Mon, 6 Mar 2017 17:54:17 -0500 Tom Rini wrote: > On Tue, Mar 07, 2017 at 12:44:59AM +0200, Siarhei Siamashka wrote: > > Hi Tom, > > > > On Mon, 6 Mar 2017 13:50:10 -0500 > > Tom Rini wrote: > > > > > Today, we have cases where we wish to build all of U-Boot in Thumb2 mode for > > > various reasons. We also have cases where we only build SPL in Thumb2 mode due > > > to size constraints and wish to build the rest of the system in ARM mode. > > > > Is there a good real world example of this particular use case? Even if > > there is enough space for having the U-Boot binary built in ARM mode, > > Thumb2 is still smaller and loads faster. And having reduced boot time > > is always nice. > > So, good question. At the moment, I'm not trying to change existing > behavior. I also seem to recall that Thumb2 being a performance win > depends on what you're doing. It would certainly be worth doing some > tests to see if on say Allwinner where today we don't do the main U-Boot > in Thumb2 mode there is a noticable change as it looked like a pretty > big size win. Hmm, you are right. Currently the 'sunxi-common.h' file has the following lines: #if defined(CONFIG_SPL_BUILD) && !defined(CONFIG_ARM64) #define CONFIG_SYS_THUMB_BUILD /* Thumbs mode to save space in SPL */ #endif I even did not know and was not careful enough to ever notice that sunxi builds the main U-Boot binary in ARM mode. This just seems to be weird. Basically, you are introducing two separate Kconfig options just to accommodate the current sunxi configuration, right? I guess, the next step would be to fix sunxi to use Thumb2 everywhere :-) Now your patch at least makes sense and looks good to me. Acked-by: Siarhei Siamashka -- Best regards, Siarhei Siamashka