Hi Huacai, On Tue, Jul 10, 2018 at 07:45:22PM +0800, 陈华才 wrote: > I don't think this is a hardware bug, in design, SFB will flushed to L1 > cache in three cases: > 1, data in SFB is full (be a complete cache line); > 2, there is a subsequent read access in the same cache line; > 3, a 'sync' instruction is executed. I'd expect successful LL/SC, cache maintenance (and potentially TLB) operations to flush your SFB as well, not that I think that provides a better workaround than throwing a 'sync' into cpu_relax(). I assume the SFB is all physically addressed? Generally, CPU architectures guarantee that store buffers drain "in finite time" which is a pretty crappy guarantee, but one which tends to be sufficient in practice and therefore relied upon by software. Will
