freebsd-skq/sys/conf/options.amd64
Poul-Henning Kamp dad3b6c6fd Back in the good old days, PC's had random pieces of rock for
frequency generation and what frequency the generated was anyones
guess.

In general the 32.768kHz RTC clock x-tal was the best, because that
was a regular wrist-watch Xtal, whereas the X-tal generating the
ISA bus frequency was much lower quality, often costing as much as
several cents a piece, so it made good sense to check the ISA bus
frequency against the RTC clock.

The other relevant property of those machines, is that they
typically had no more than 16MB RAM.

These days, CPU chips croak if their clocks are not tightly within
specs and all necessary frequencies are derived from the master
crystal by means if PLL's.

Considering that it takes on average 1.5 second to calibrate the
frequency of the i8254 counter, that more likely than not, we will
not actually use the result of the calibration, and as the final
clincher, we seldom use the i8254 for anything besides BEL in
syscons anyway, it has become time to drop the calibration code.

If you need to tell the system what frequency your i8254 runs,
you can do so from the loader using hw.i8254.freq or using the
sysctl kern.timecounter.tc.i8254.frequency.
2008-03-26 22:12:00 +00:00

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# $FreeBSD$
# Options specific to AMD64 platform kernels
AUTO_EOI_1 opt_auto_eoi.h
AUTO_EOI_2 opt_auto_eoi.h
MAXMEM
PERFMON
PMAP_SHPGPERPROC opt_pmap.h
MP_WATCHDOG
# Options for emulators. These should only be used at config time, so
# they are handled like options for static filesystems
# (see src/sys/conf/options), except for broken debugging options.
COMPAT_IA32 opt_compat.h
#IBCS2 opt_dontuse.h
#COMPAT_LINUX opt_dontuse.h
COMPAT_LINUX32 opt_compat.h
#COMPAT_SVR4 opt_dontuse.h
#DEBUG_SVR4 opt_svr4.h
LINPROCFS opt_dontuse.h
LINSYSFS opt_dontuse.h
NDISAPI opt_dontuse.h
TIMER_FREQ opt_clock.h
# options for serial support
COM_ESP opt_sio.h
COM_MULTIPORT opt_sio.h
CONSPEED opt_sio.h
GDBSPEED opt_sio.h
COM_NO_ACPI opt_sio.h
VGA_ALT_SEQACCESS opt_vga.h
VGA_DEBUG opt_vga.h
VGA_NO_FONT_LOADING opt_vga.h
VGA_NO_MODE_CHANGE opt_vga.h
VGA_SLOW_IOACCESS opt_vga.h
VGA_WIDTH90 opt_vga.h
ATKBD_DFLT_KEYMAP opt_atkbd.h
# -------------------------------
# isdn4bsd: passive PCI cards
# -------------------------------
ELSA_QS1PCI opt_i4b.h
# -------------------------------
# isdn4bsd: misc options
# -------------------------------
# temporary workaround for SMP machines
I4B_SMP_WORKAROUND opt_i4b.h
# enable VJ compression code for ipr i/f
#XXXBZ#IPR_VJ opt_i4b.h
#XXXBZ#IPR_LOG opt_i4b.h
# -------------------------------
# EOF
# -------------------------------
HAMMER opt_cpu.h
PSM_HOOKRESUME opt_psm.h
PSM_RESETAFTERSUSPEND opt_psm.h
PSM_DEBUG opt_psm.h
DEV_ATPIC opt_atpic.h
# Debugging
STOP_NMI opt_cpu.h
# BPF just-in-time compiler
BPF_JITTER opt_bpf.h