On Monday, 23 April 2012, Thomas Meyer wrote: > Am Sonntag, den 22.04.2012, 22:34 -0400 schrieb Chris Tyler: > > On Sun, 2012-04-22 at 18:16 -0700, Brendan Conoboy wrote: > > > As we get closer to having 100% package coverage in F17-ARM we're > > > running into harder build failures due to the limitations of the chips > > > we're building for. The problem I've noticed on many of the recent > > > failures is due to the lack of atomic operations (These didn't arrive > > > until ARMv6). > > > 6. There is the kernel's "user space atomic helper" (kuser_cmpxchg64) at > > 0xffff0f60, see Documentation/arm/kernel_user_helpers.txt. The kernel > > puts an instruction sequence here tuned for the current arch that can be > > called by userland to provide an atomic compare/exchange -- if it can be > > done natively, the instruction sequence does that, otherwise it does a > > syscall (with IRQ protection etc). Would this solve the problems you've > > identified? > > I'm running the Ubuntun 2.6.38 Tegra2 kernel (because of their fbdev > support) on top of Fedora 17 armv5el on an Toshiba AC100 Laptop. The > rsyslog package crashed everytime because of the missing kernel support > of cmpxchg64. So when relying on the kernel helpers make sure that the > resp. kernel support exists. > >
If you used the 64 bit gcc sync primitives and they called the helper functions IIRC there is a check in there for the existence and graceful abort of these handlers... Ramana > with kind regards > thomas > > _______________________________________________ > arm mailing list > arm@lists.fedoraproject.org <javascript:;> > https://admin.fedoraproject.org/mailman/listinfo/arm
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