Hi Jeroen, On Thu, 11 Sep 2014 13:17:20 +0200, Jeroen Hofstee <[email protected]> wrote:
> Hello Albert, > > On do, 2014-09-11 at 10:32 +0200, Albert ARIBAUD wrote: > > > > > On Wed, 10 Sep 2014 20:08:50 +0200, Jeroen Hofstee > > <[email protected]> wrote: > > > > > Changes since v2: > > > - As Albert pointed out the clang instructions don't work with > > > Debian based binary packages. While I was aware of that it is > > > for a different reason then I thought, it is not that ARM is not > > > enabled as a backend but older versions are a bit more picky on > > > the target argument and don't tolerate a trailing dash to it as > > > used for CROSS_COMPILE etc. The README is updated accordingly. > > > > > > As a side note clang3.5-svn as shipped in Ubuntu is not the 3.5 > > > release but an snapshot of some svn commit and hence explain why > > > the recompiled 3.5 can behave different then the ubuntu clang-3.5. > > > Since it misses some patches, the clang3.5-svn can build less > > > boards then 3.4 or an actual 3.5 release. > > > > > > - While add it, include Masahiro suggestion to also use c++ instead > > > of g++. > > > - Drop dependencies from the cover-letter as they are merged. > > > - only patch 7/8 and 8/8 are reposted. 1..6 are the same as v2. > > > > Thanks, tested building rpi_b, it works now. > > > > The, tested on versatileqemu out of curiosity and got the following > > results: > > > > 1. > > > > clang warns about Unused static functions in common/console.c, namely > > console_printdevs and console_doenv (1). Why gcc does not flag this? > > We have -Wall set which is supposed to imply -Wunused-functions. > > It is a gcc feature, see [1]: "Warn whenever a static function is > declared but not defined or a _non-inline static function_ is unused. > This warning is enabled by -Wall." Ok, I'll assume there is some logic in there, but then, clang does not follow that logic -- so which one is the 'good' one? Or maybe that's the same as the second issue, where... > > There is also an unused variable warning in disk/part.c28 > > (block_drvr). I haven't looked at why clang warns about it and not gcc, > > but it could raise the same question as the functions above. > > Also a gcc feature, see [2]. The constant is indeed not used. ... apparently, it's a case of trying to balance false positives and missed true issue, and each team has its own view of where to set the limit. :/ (anyway -- here clearly, clang is right in warning us and gcc is wrong in not doing it) > > 2. > > > > clang errors on arch/arm/lib/cache.c:28 for this: > > asm("0: mrc p15, 0, r15, c7, c10, 3\n\t" "bne 0b\n" : : : "memory"); > > and that is a clang mistake, as for ARM926EJS r15 is a valid (albeit > > quite special semantically) Rd for Test and Clean DCache, see page 2-24. > > > > This is the integrated-as complaining (the README tells you to disable > it for the moment). The clang folks push UAL hard, up to a point we need > to think about minimum gcc version etc. To avoid that, I just left out > such changes and just use gas instead, at least for the time being. > Below are some changes to compile versatileqemu with llvm integrated-as > and gcc/gas. No idea if it actually boots though. > > > Jeroen, do you feel like raising point 2 to the clang/LLVM folks? > > It is removed on purpose as far as I understood. I don't think they > regards it as a bug, see obfuscated patch below. > > > Other than that, the patch series seems to be good. I'll apply it > > soonish. > > > > Thanks, > Jeroen > ~ "mrc p15, 0, r15, c7, c14, 3\n" > + "mrc p15, 0, apsr_nzcv, c7, c14, 3\n" Is this is a hack to set the Rd field of the mrc instruction to a value equal to what "r15" would have given, but fooling clang by using an unrelated and, in this context, meaningless, symbol instead of "r15"? Amicalement, -- Albert. _______________________________________________ U-Boot mailing list [email protected] http://lists.denx.de/mailman/listinfo/u-boot
