On 03/24/2016 12:47 AM, Sergey Kubushyn wrote: > On Thu, 24 Mar 2016, Marek Vasut wrote: > >> On 03/24/2016 12:08 AM, Tom Rini wrote: >>> On Wed, Mar 23, 2016 at 04:02:07PM -0700, Sergey Kubushyn wrote: >>>> On Wed, 23 Mar 2016, Tom Rini wrote: >>>> >>>>> On Wed, Mar 23, 2016 at 06:08:45PM +0100, Albert ARIBAUD wrote: >>>>>> Hello Tom, >>>>>> >>>>>> On Wed, 23 Mar 2016 09:22:38 -0400, Tom Rini <tr...@konsulko.com> >>>>>> wrote: >>>>>>> On Wed, Mar 23, 2016 at 01:53:35PM +0100, Albert ARIBAUD wrote: >>>>>>>> Hello Marek, >>>>>>>> >>>>>>>> On Sun, 20 Mar 2016 17:15:34 +0100, Marek Vasut <ma...@denx.de> >>>>>>>> wrote: >>>>>>>>> This patch decouples U-Boot binary from the toolchain on >>>>>>>>> systems where >>>>>>>>> private libgcc is available. Instead of pulling in functions >>>>>>>>> provided >>>>>>>>> by the libgcc from the toolchain, U-Boot will use it's own set >>>>>>>>> of libgcc >>>>>>>>> functions. These functions are usually imported from Linux >>>>>>>>> kernel, which >>>>>>>>> also uses it's own libgcc functions instead of the ones >>>>>>>>> provided by the >>>>>>>>> toolchain. >>>>>>>>> >>>>>>>>> This patch solves a rather common problem. The toolchain can >>>>>>>>> usually >>>>>>>>> generate code for many variants of target architecture and >>>>>>>>> often even >>>>>>>>> different endianness. The libgcc on the other hand is usually >>>>>>>>> compiled >>>>>>>>> for one particular configuration and the functions provided by >>>>>>>>> it may >>>>>>>>> or may not be suited for use in U-Boot. This can manifest in >>>>>>>>> two ways, >>>>>>>>> either the U-Boot fails to compile altogether and linker will >>>>>>>>> complain >>>>>>>>> or, in the much worse case, the resulting U-Boot will build, >>>>>>>>> but will >>>>>>>>> misbehave in very subtle and hard to debug ways. >>>>>>>> >>>>>>>> I don't think using private libgcc by default is a good idea. >>>>>>>> >>>>>>>> U-Boot's private libgcc is not a feature of U-Boot, but a fix >>>>>>>> for some >>>>>>>> cases where a target cannot properly link with the libgcc >>>>>>>> provided by >>>>>>>> the (specific release of the) GCC toolchain in use. Using >>>>>>>> private libgcc >>>>>>>> to other cases than these does not fix or improve anything; those >>>>>>>> other cases were working and did not require any fix in this >>>>>>>> respect. >>>>>>> >>>>>>> This isn't true, exactly. If using clang for example everyone >>>>>>> needs to >>>>>>> enable this code. We're also using -fno-builtin -ffreestanding >>>>>>> which >>>>>>> should limit the amount of interference from the toolchain. And >>>>>>> we get >>>>>>> that. >>>>>> >>>>>> You mean clang does not produce self-sustained binaries? >>>>> >>>>> clang does not provide "libgcc", so there's no -lgcc providing all of >>>>> the functions that are (today) in: >>>>> _ashldi3.S _ashrdi3.S _divsi3.S _lshrdi3.S _modsi3.S _udivsi3.S >>>>> _umodsi3.S div0.S _uldivmod.S >>>>> which aside from __modsi3 and __umodsi3 are all __aeabi_xxx >>>> >>>> There is also _udivmoddi4 pulled from libgcc for 64-bit division >>>> since we >>>> switched to 64-bit all around ARM. It comes from clock calculations for >>>> video, e.g. from drivers/video/ipu_common.c for i.MX6. >>> >>> Well, this is an example of why we both don't want libgcc ever nor do we >>> want to overly expand what we do offer. In this case isn't it an >>> example of something that should be using lldiv/do_div/etc? >> >> I haven't seen the _udivmoddi4 emitted in my tests. Linux's libgcc copy >> also doesn't implement the function. Which toolchain do you use and >> which target did you compile? > > I'm using my own armv7hl-linux-gnueabi toolchain built for hard float. > Linux > arm libgcc does have arch/arm/lib/div64.S file that provides __do_div64() > function that is used by do_div() from include/asm/div64.h for 32-bit ARM > platform. Sure, arm64 has neither div64.h nor div64.S. We _DO_ have div64.h > (that is totally different from what Linux provides) but no div64.S in > arch/arm/lib.
In that case, we should just import div64.S from Linux on arm32 and be done with it ? Since we now have all the necessary macros thanks to the first four patches in this series, that should be trivial. What do you think? I can bake a patch real quick, so you can test it ? Best regards, Marek Vasut _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
