store init functions for the UltraSPARC T1 processors need membar, otherwise a networking oops can be easily triggered with high traffic (i.e. netcat on localhost). See http://marc.info/?l=linux-sparc&m=117429003730831&w=2 and http://marc.info/?l=linux-sparc&m=117321135122528&w=2
Created attachment 113776 [details, diff] Niagara membar patch
Fixed in gentoo-sources-2.6.20-r4, thanks.