On Sun, Jun 20, 2010 at 09:33:29PM +0000, Alexander Motin wrote: > Author: mav > Date: Sun Jun 20 21:33:29 2010 > New Revision: 209371 > URL: http://svn.freebsd.org/changeset/base/209371 > > Log: > Implement new event timers infrastructure. It provides unified APIs for > writing event timer drivers, for choosing best possible drivers by machine > independent code and for operating them to supply kernel with hardclock(), > statclock() and profclock() events in unified fashion on various hardware. > > Infrastructure provides support for both per-CPU (independent for every CPU > core) and global timers in periodic and one-shot modes. MI management code > at this moment uses only periodic mode, but one-shot mode use planned for > later, as part of tickless kernel project. > > For this moment infrastructure used on i386 and amd64 architectures. Other > archs are welcome to follow, while their current operation should not be > affected. > > This patch updates existing drivers (i8254, RTC and LAPIC) for the new > order, and adds event timers support into the HPET driver. These drivers > have different capabilities: > LAPIC - per-CPU timer, supports periodic and one-shot operation, may > freeze in C3 state, calibrated on first use, so may be not exactly precise. > HPET - depending on hardware can work as per-CPU or global, supports > periodic and one-shot operation, usually provides several event timers. > i8254 - global, limited to periodic mode, because same hardware used also > as time counter. > RTC - global, supports only periodic mode, set of frequencies in Hz > limited by powers of 2. > > Depending on hardware capabilities, drivers preferred in following orders, > either LAPIC, HPETs, i8254, RTC or HPETs, LAPIC, i8254, RTC. > User may explicitly specify wanted timers via loader tunables or sysctls: > kern.eventtimer.timer1 and kern.eventtimer.timer2. > If requested driver is unavailable or unoperational, system will try to > replace it. If no more timers available or "NONE" specified for second, > system will operate using only one timer, multiplying it's frequency by few > times and uing respective dividers to honor hz, stathz and profhz values, > set during initial setup.
This broke QEMU for me. I cannot boot FreeBSD guest under QEMU anymore. QEMU (not FreeBSD kernel) panics with qemu: level-triggered hpet not supported message. Setting kern.eventtimer.timer1 to LAPIC or i8254, and timer2 to NONE does not help.
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