On Thu, 5 Sep 2013, Ralf Baechle wrote: > > This change corrects DECstation HRT calibration, by removing the following > > bugs: > > Hmm... Seems this needs to be applied to virtually every older kernel > as well almost back to the dawn? Yeah, any version that's still considered maintained; regrettably I've lost track of what the current practices are. What about the R4k timer erratum workaround fix I sent the other day? I'll have another small fix in this area yet, for a hopefully better decision on what to select from the timers available on various DECstation systems that have small differences among them. > Great to see you backon the DECstations! I'm glad to have some time to have a look. The platform seems to suffer from surprisingly little bitrot, there are some issues with the system clock as handled with these patches and with the RTC -- regrettably drivers/char/rtc.c isn't selectable anymore (any particular reason for that?) and the potential rtclib drivers (drivers/rtc/rtc-cmos.c or drivers/rtc/rtc-m48t86.c) refuse to cooperate with hardware. Also the IRQ handling latency has become high enough now for the serial driver to lose characters received at 115200bps on the R3400 system (the R4400 one is fast enough to cope). Other than these I haven't noticed any issues with the 32-bit kernel -- that in a proper classic style netboots smoothly albeit a bit slowly via MOP over FDDI and fully cooperates with the userland. Unfortunately that can't be said of the 64-bit kernel that hangs solidly (reset does not help, need to power-cycle) early on, after: Linux version 3.11.0-rc2 (macro@tp) (gcc version 4.1.2) #1 Sun Sep 1 18:06:20 BST 2013 bootconsole [prom0] enabled has been printed. The next line should be: This is a DECstation 5000/2x0 So the hang happens somewhere between register_prom_console and prom_identify_arch, both called from prom_init, very early indeed. I'll have a look into it next; hopefully it's something silly rather than my old trusty compiler getting confused with something added somewhere meanwhile. This is an R4400SC BTW, initial revision (PRId: 00000440). I'm not sure what to do about the RTC yet, and the Zilog SCC@115200bps case is probably lost even though the chip has been wired for DMA in the DECstation. Maciej
