On Wed, 05 May 2010 08:43:16 -0700, "Kevin D. Kissell" <kevink@xxxxxxxxxxxxx> wrote: > >> I'm glad to hear that the patch is functional. It was pretty clear that > >> it would solve your problem, but I was concerned that the inability to > >> write the Cause bits was done as a way around some other problem. > >> Someone went to a certain amount of trouble to not accept them as > >> inputs, in violation of spec. I just looked back, and the bug was > >> introduced as part of a patch of Ralf's from April 2005 entitled "Fix > >> Preemption and SMP problems in the FP emulator". It's unlikely that > >> overriding CTC semantics actually fixed any underlying problems, but it > >> may have masked symptoms of problems that we can only hope have been > >> fixed in the mean time. Anyone run this patch on an FPUless SMP? Oh, > >> for a 34Kf with a bunch of TCs! ;o) > >> > > > > That's commit ID 72402ec9efdb2ea7e0ec6223cf20e7301a57da02 and the patch > > was comitted during the CVS days which only records the comitter but not > > the author. The actual author is Atsushi Nemoto. > > > Well,. I certainly understood that you were simply the guy who did the > commit. Didn't mean to make it sound like an accusation, but it was > marginally easier to type your name and date than to find, cut, and > paste the commit ID. Sorry if it came off wrong. It would be cool if > Atsushi remembered the reasoning behind the change, but empirical proof > that undoing it doesn't create a subtle problem for current SMP kernels > would be better still. Yes, that's my patch. Though I cannot remember precisely, maybe I just had (mis)thought Cause bits in FCSR are read-only at that time. I have never used real SMP MIPS platforms, so there must be no SMP-related issues. I'm OK with Kevin's fix. Thank you very much for reporting and investigating. --- Atsushi Nemoto
