On Tue, Mar 07, 2017 at 03:02:05AM +0200, Siarhei Siamashka wrote: > On Mon, 6 Mar 2017 17:54:17 -0500 > Tom Rini <[email protected]> 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 <[email protected]> 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?
Along with some at91 (arm926ej-s based) platforms. In all cases the root problem was "Oh, we can't fit SPL in our size constraint, lets tweak it like this". -- Tom
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