On 04/24/2012 07:39 AM, Nicolas Pitre wrote: > On Tue, 24 Apr 2012, Andrew Haley wrote: > >> On 04/23/2012 09:31 PM, Nicolas Pitre wrote: >>> On Mon, 23 Apr 2012, Andrew Haley wrote: >>> >>>> On 04/23/2012 06:36 PM, Thomas Meyer wrote: >>>>> 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. >>> >>> Kernel helpers don't disappear with time. You therefore can probe for >>> their availability (see the documentation) in case the kernel support >>> could be backported, or just refuse to run if the kernel version isn't >>> recent enough. This is not much different from relying on a new >>> syscall. >> >> Indeed it is. What would I gain from adding such a test? All I can >> see is extra complication, untested code paths, and larger programs. > > What alternative do you have, other than not using any atomic > operations? > >> The untested code path is particularly nasty. > > How buggy the following code might be: > > fprintf(stderr, "Your kernel is too old, aborting\n") > exit(1); > > ? > > > Nicolas Checking kernel characteristics of the running kernel on a Fedora build system might not be a good idea. The build system might be a chroot jail on an older release (for example fedora 17 chroot on fedora 15). This was a problem when building the early versions of the papi RPMs. RHEL6 build roots were on RHEL5 machines. Checking the kernel version with a "uname -r" showed a kernel RHEL5 kernel that didn't have the need perf support. However, things were being built for a RHEL6 so this test was misleading. Is it possible to get this information from kernel-headers rather than probing the running kernel? -Will _______________________________________________ arm mailing list arm@xxxxxxxxxxxxxxxxxxxxxxx https://admin.fedoraproject.org/mailman/listinfo/arm
