christophe lombard <clomb...@linux.vnet.ibm.com> writes: > Le 20/12/2017 à 09:46, Vaibhav Jain a écrit : >>> In fact, it does not matter. I don't know what the userspace could do >>> with this value. >> Without libcxl knowing the tidr value, it cannot enforce the condition >> that only threads that have called attach can issue 'wait' on the right >> context. >> >> Also AFU can selectively ask PSL to issue asb_notify to a specific >> thread via the PSL interface. Without userspace knowing the tidr value >> it might not be easy for it to give this value to AFU through a Problem >> State Area register. >> > > Don't forget that The ASB_Notify will use LPID:PID:TID tuple found > in the Process Element Entry. > The AFU may optionally provide a TID on AxH_CEA[40:55] (AxH_CEA[39] > must be set to indicate an AFU provided TID) > If AxH_CEA[39] == 1’b0 then Process Element information > (LPID:PID:TID) is used to generate the PCIe address. > If AxH_CEA[39] == 1’b1then the LPID:PID are taken from the PEE > while the TID is taken from AxH_-CEA[40:55]
Agree and that was the point I was trying to make when I said that AFU can selectivly issue asb_notify to a thread. Without userspace threads knowing their tidr libcxl would let any thread issue the 'wait' instruction that may cause unpredictable results. -- Vaibhav Jain <vaib...@linux.vnet.ibm.com> Linux Technology Center, IBM India Pvt. Ltd.