svn commit: r209371 - in head/sys: amd64/amd64 amd64/include
conf dev/acpica i386/i386 i386/include isa kern pc98/cbus sys
pawel.worach at gmail.com
Mon Jun 21 20:15:04 UTC 2010
On Jun 21, 2010, at 21:58, Kostik Belousov wrote:
> 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
>> 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
>> 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
> Setting kern.eventtimer.timer1 to LAPIC or i8254, and timer2 to NONE
> does not help.
ps. level-triggered hpet is implemented in QEMU git.
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