[fedora-arm] ARMv5 and atomic operations

Nicolas Pitre nico at fluxnic.net
Mon Apr 23 20:31:39 UTC 2012


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.


Nicolas


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