Hello Albert, On Tue, 24 Feb 2015 14:53:36 +0100, Albert ARIBAUD <albert.u.b...@aribaud.net> wrote: > When building a THumb-1-only target with CONFIG_SYS_THUMB_BUILD, > some files fail to build, most of the time because they include > mcr instructions, which only exist for Thumb-2. > > Thos patch introduces a Kconfig option CONFIG_THUMB2 and uses > it to select between Thumb-2 and ARM mode for the aforementioned > files. > > Signed-off-by: Albert ARIBAUD <albert.u.b...@aribaud.net> > --- > This patch has been build-tested and run-tested on ED Mini V2, > above the "edmini: switch to SPL" patch, and found to reduce > U-Boot size by 25% and SPL size by 14%... and to run fine. :) > > This patch has also been tested against side effects on the > non-Thumb wireless_space target. The binaries produced with > and without ths patch were found to differ only by their > version string. > > Changes in v2: > - fixed a typo in the commit message > - added file arch/arm/thumb1/include/asm/proc-armv/system.h, > which overrides arch/arm/include/asm/proc-armv/system.h > when building for Thumb-1 and provides non-functional but > Thumb-compilable IRQ and FIQ related macros and functions.
Ok, this does not fare as good as I have hoped, because there are also thumb1-unfrendly macros in arch/arm/include/asm/cache.h, this time with mcr and mrc instructions. /me hates macros used as inline functions. :( I cannot just replace the macros with empty inline functions as I did with arch/arm/include/asm/proc-armv/system.h, since this would cause cache to not work. :( This leaves only one solution: when buildding for thumb1, replace the macros in cache.h with plain function prototypes, and provide simple ARM-state implementations for these. We'll lose a bit of performance as instead of a single mcr or mrc instruction, we'll have a call switching from Thumb to ARM state, the mcr/mrc instruction, and a return to Thumb state. Hopefully that won't hurt performance too much. V3 in the works. Amicalement, -- Albert. _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot