On Thu, Jun 14, 2018 at 12:12 PM Andre McCurdy <[email protected]> wrote: > > On Thu, Jun 14, 2018 at 9:40 AM, Khem Raj <[email protected]> wrote: > > On 6/14/18 5:10 AM, Herve Jourdain wrote: > >> Hi, > >> > >> I believe I solved that same problem by just adding, in the case of armv8 > >> (which I believe may be the new architecture you're referring to): > >> MUTEX_armv8 = "" > >> This way, it allows previous versions to work just like they did before, > >> without having to disable ARM assembler mutex code for architectures that > >> support it correctly - up to armv7ve I believe. > >> Of course, we might need to also have a good definition for armv8, which is > >> the object of another thread. > > > > right thats a better approach. > > SWP is not guaranteed to work on SMP systems... and even if it does, > performance is likely to be worse than the pthreads version (which can > take advantage of the newer instructions). > > > https://community.arm.com/processors/b/blog/posts/locks-swps-and-two-smoking-barriers > > In general, use of hand optimised assembler mutex implementations in > user space isn't something to be encouraged - use pthreads (or maybe a > gcc intrinsic) instead. >
question is about disabling it on old arm machines, do we have data where we know that other sync methods without swp works better on armv5 and lower ? Do we have gcc intrinsics for those versions of arm ? if we do then I think I would agree > I think the original patch is good. > > >> Cheers, > >> Herve > >> > >> -----Original Message----- > >> From: [email protected] > >> [mailto:[email protected]] On Behalf Of > >> Ovidiu Panait > >> Sent: jeudi 14 juin 2018 13:55 > >> To: [email protected] > >> Subject: [OE-core] [PATCH 1/1] db: disable the ARM assembler mutex code > >> > >> The swpb in macro MUTEX_SET will cause "undefined instruction" error on the > >> new arm arches which don't support this assembly instruction any more. If > >> use ldrex/strex to replace swpb, the old arm arches don't support them. So > >> to avoid this issue, just disable the ARM assembler mutex code, and use the > >> default pthreads mutex. > >> > >> Signed-off-by: Li Zhou <[email protected]> > >> Signed-off-by: Catalin Enache <[email protected]> > >> Signed-off-by: Ovidiu Panait <[email protected]> > >> --- > >> meta/recipes-support/db/db_5.3.28.bb | 13 +------------ > >> 1 file changed, 1 insertion(+), 12 deletions(-) > >> > >> diff --git a/meta/recipes-support/db/db_5.3.28.bb > >> b/meta/recipes-support/db/db_5.3.28.bb > >> index 093ee44909..15b4155a29 100644 > >> --- a/meta/recipes-support/db/db_5.3.28.bb > >> +++ b/meta/recipes-support/db/db_5.3.28.bb > >> @@ -59,18 +59,7 @@ FILES_SOLIBSDEV = "${libdir}/libdb.so > >> ${libdir}/libdb_cxx.so" > >> # All the --disable-* options replace --enable-smallbuild, which breaks a > >> bunch of stuff (eg. postfix) DB5_CONFIG ?= "--enable-o_direct > >> --disable-cryptography --disable-queue --disable-replication > >> --disable-verify --disable-compat185 --disable-sql" > >> > >> -EXTRA_OECONF = "${DB5_CONFIG} --enable-shared --enable-cxx --with-sysroot" > >> - > >> -# Override the MUTEX setting here, the POSIX library is -# the default - > >> "POSIX/pthreads/library". > >> -# Don't ignore the nice SWP instruction on the ARM: > >> -# These enable the ARM assembler mutex code, this won't -# work with thumb > >> compilation... > >> -ARM_MUTEX = "--with-mutex=ARM/gcc-assembly" > >> -MUTEX = "" > >> -MUTEX_arm = "${ARM_MUTEX}" > >> -MUTEX_armeb = "${ARM_MUTEX}" > >> -EXTRA_OECONF += "${MUTEX} STRIP=true" > >> +EXTRA_OECONF = "${DB5_CONFIG} --enable-shared --enable-cxx --with-sysroot > >> STRIP=true" > >> EXTRA_OEMAKE += "LIBTOOL='./${HOST_SYS}-libtool'" > >> > >> EXTRA_AUTORECONF += "--exclude=autoheader -I ${S}/dist/aclocal > >> -I${S}/dist/aclocal_java" > >> -- > >> 2.17.1 > >> > >> -- > >> _______________________________________________ > >> Openembedded-core mailing list > >> [email protected] > >> http://lists.openembedded.org/mailman/listinfo/openembedded-core > >> > > > > > > > > -- > > _______________________________________________ > > Openembedded-core mailing list > > [email protected] > > http://lists.openembedded.org/mailman/listinfo/openembedded-core > > -- _______________________________________________ Openembedded-core mailing list [email protected] http://lists.openembedded.org/mailman/listinfo/openembedded-core
