On Sun, May 26, 2019 at 08:14:43PM +0200, Jasper Lievisse Adriaanse wrote: > Hi, > > Whilst looking at the mc146818 code in vmd I noticed something that initially > struck > me as a pasto as the same code is present in the rtc_update_regb() function. > However > it led me to look at how other emulators handle the updating of registers. > Based on > that here's a diff to only reschedule the periodic interrupt after updating > register A > if something changed in register A. > > When updating register A we were checking in register B if the > PIE bit was set in order to decide if rtc_reschedule_per needed > to be called. if that bit was changed then the timer rate would > already have been adjusted by rtc_update_regb so the call from > rtc_update_rega is not needed. This now matches what qemu and > other emulators are doing too. > > This has been running fine for a few days in a number of VMs. > > OK? >
sure, ok mlarkin > Index: mc146818.c > =================================================================== > RCS file: /cvs/src/usr.sbin/vmd/mc146818.c,v > retrieving revision 1.18 > diff -u -p -r1.18 mc146818.c > --- mc146818.c 12 Jul 2018 10:15:44 -0000 1.18 > +++ mc146818.c 26 May 2019 12:13:32 -0000 > @@ -216,7 +216,7 @@ rtc_update_rega(uint32_t data) > __func__); > > rtc.regs[MC_REGA] = data; > - if (rtc.regs[MC_REGB] & MC_REGB_PIE) > + if ((rtc.regs[MC_REGA] ^ data) & 0x0f) > rtc_reschedule_per(); > } > > > -- > jasper >
