On 04/23/2012 06:36 PM, 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.
Indeed. I had to write a workaround in IcedTea (i.e. java) on ARM for just this reason. If you can't depend on a kernel helper being there I can't see it's of any use. Andrew. _______________________________________________ arm mailing list arm@lists.fedoraproject.org https://admin.fedoraproject.org/mailman/listinfo/arm
