On 2017-05-18 03:55, Thomas Huth wrote: > On 17.05.2017 18:49, David Hildenbrand wrote: > > On 17.05.2017 17:35, Thomas Huth wrote: > > 2. I would recommend to not enable STFLE for now. Why? > > > > It is/was an indication that the system is running on a z9 (and > > implicitly has the basic features). This was not only done because > > people were lazy, but because this bit was implicitly connected to other > > machine properties. > > Uh, that's ugly! > > > One popular example is the "DAT-enhancement facility 2". It introduced > > the "LOAD PAGE TABLE ENTRY ADDRESS" instruction, but no facility bit was > > introduced. SO there is no way to check if the instruction is available > > and actually working. > > Does the Linux kernel use this instruction at all? I just grep'ed > through the kernel sources and did not find it. If the Linux kernel does > not use it, I think we should ignore this interdependency and just > provide the STFLE feature bit to the guest - since recent Linux kernels > depend on it. > > > Please note that we added a feature representation for this facility, > > because this would allow us later on to at least model removal of such a > > facility (if HW actually would drop it) on a CPU model level. > > What about STFLE bit 78, according to my version of the POP, it says: > > "The enhanced-DAT facility 2 is installed in the > z/Architecture architectural mode."
No that is different. IBM has chosen very confusing names for the DAT related facilities: - DAT-Enhancement Facility 1 => bits 3, 4 & 5 - DAT-Enhancement Facility 2 - Enhanced-DAT Facility 1 => bit 8 - Enhanced-DAT Facility 2 => bit 78 Aurelien -- Aurelien Jarno GPG: 4096R/1DDD8C9B aurel...@aurel32.net http://www.aurel32.net
