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As we many times by now discussed that - some ARC cores might not have atomic instructions implemented. Namely that's ARC700 w/o explicitly added atomics during design creation/configuration. Because of that when GCC gets configured for ARC700, i.e. via "--with-cpu=arc700" atomic ops are assumed disabled. Usually it's not a problem as we add "-matomics" in the wraper for building all packages if targets CPU has atomis (BR2_ARC_ATOMIC_EXT). But when bulding target's binaries which are essential parts of the GCC itself we don't use the wrapper. Instead xgcc is being used. That way we lose that important part of system's configuration about atomics and: 1. Atomic ops won't be used where otherwise they could have been used. 2. Some configuration checks might end-up thinking there're no atomics In particular (2) leads to pretty obscure failure on bulding of some packages which use C++, for example: log4cplus: http://autobuild.buildroot.net/results/a7732fdb2ba526a114d9fb759814236c5332f8d7 ------------------------>8-------------------- ./.libs/liblog4cplus.so: undefined reference to `std::__atomic_futex_unsigned_base::_M_futex_notify_all(unsigned int*)' collect2: error: ld returned 1 exit status ------------------------>8-------------------- bitcoin: http://autobuild.buildroot.net/results/f73/f73d4c77e5fd6223abdbc83e344addcfc93227b8 ------------------------>8-------------------- (.text+0x110c): undefined reference to `std::__atomic_futex_unsigned_base::_M_futex_wait_until(unsigned int*, unsigned int, bool, std::chrono::duration<long long, std::ratio<1ll, 1ll> >, std::chrono::duration<long long, std::ratio<1ll, 1000000000ll> >)' collect2: error: ld returned 1 exit status ------------------------>8-------------------- apcupsd: http://autobuild.buildroot.net/results/7a2/7a2cc7a4ac2237c185817f75e55e05d144efd100 ------------------------>8-------------------- /tmp/instance-0/output-1/host/lib/gcc/arc-buildroot-linux-uclibc/9.3.1/../../../../arc-buildroot-linux-uclibc/bin/ld: eh_throw.cc:(.text._ZL23__gxx_exception_cleanup19_Unwind_Reason_CodeP17_Unwind_Exception+0x24): undefined reference to `__gnu_cxx::__exchange_and_add(int volatile*, int)' collect2: error: ld returned 1 exit status ------------------------>8-------------------- ...and many more. Interesting enough that was not seen earlier because "-matomic" used to be added in TARGET_{C|CXX}FLAGS via TARGET_ABI, but later "-matomic" was moved to ARCH_TOOLCHAIN_WRAPPER_OPTS, see https://git.buildroot.org/buildroot/commit/?id=c568b4f37fa6d7f51e6d14d33d7eb75dfe26d7bf and since then we started to see that new breakage which we now attempt to fix right where it hapens on GCC configuration. In contrast ARC HS family has atomic ops enabled by default thus we never spotted that kind of problem for it. More datails with analysis of what really happens under the hodd and how do error messages above are related to libs of GCC configuration could be found here: http://lists.busybox.net/pipermail/buildroot/2020-October/293614.html Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com> Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com> Cc: Arnout Vandecappelle <arnout@mind.be> Cc: Peter Korsgaard <peter@korsgaard.com> Cc: Romain Naour <romain.naour@gmail.com> [Peter: simplify conditional] Signed-off-by: Peter Korsgaard <peter@korsgaard.com> |
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| fs | ||
| linux | ||
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| system | ||
| toolchain | ||
| utils | ||
| .defconfig | ||
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| Config.in | ||
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| Makefile | ||
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| README | ||
Buildroot is a simple, efficient and easy-to-use tool to generate embedded Linux systems through cross-compilation. The documentation can be found in docs/manual. You can generate a text document with 'make manual-text' and read output/docs/manual/manual.text. Online documentation can be found at http://buildroot.org/docs.html To build and use the buildroot stuff, do the following: 1) run 'make menuconfig' 2) select the target architecture and the packages you wish to compile 3) run 'make' 4) wait while it compiles 5) find the kernel, bootloader, root filesystem, etc. in output/images You do not need to be root to build or run buildroot. Have fun! Buildroot comes with a basic configuration for a number of boards. Run 'make list-defconfigs' to view the list of provided configurations. Please feed suggestions, bug reports, insults, and bribes back to the buildroot mailing list: buildroot@buildroot.org You can also find us on #buildroot on Freenode IRC. If you would like to contribute patches, please read https://buildroot.org/manual.html#submitting-patches