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[Qemu-devel] [PATCH 1/4] vl: improve/fix documentation related to RTC fu
From: |
Artem Pisarenko |
Subject: |
[Qemu-devel] [PATCH 1/4] vl: improve/fix documentation related to RTC function |
Date: |
Thu, 11 Oct 2018 18:23:16 +0600 |
Documentation describing -rtc option updated to better match current
implementation and highlight some important specifics.
Signed-off-by: Artem Pisarenko <address@hidden>
---
qemu-options.hx | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)
diff --git a/qemu-options.hx b/qemu-options.hx
index f139459..4a9c065 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -3458,25 +3458,29 @@ HXCOMM Silently ignored for compatibility
DEF("clock", HAS_ARG, QEMU_OPTION_clock, "", QEMU_ARCH_ALL)
DEF("rtc", HAS_ARG, QEMU_OPTION_rtc, \
- "-rtc [base=utc|localtime|date][,clock=host|rt|vm][,driftfix=none|slew]\n"
\
+ "-rtc
[base=utc|localtime|<datetime>][,clock=host|rt|vm][,driftfix=none|slew]\n" \
" set the RTC base and clock, enable drift fix for clock
ticks (x86 only)\n",
QEMU_ARCH_ALL)
STEXI
address@hidden -rtc
[base=utc|localtime|@var{date}][,clock=host|vm][,driftfix=none|slew]
address@hidden -rtc
[base=utc|localtime|@var{datetime}][,clock=host|rt|vm][,driftfix=none|slew]
@findex -rtc
Specify @option{base} as @code{utc} or @code{localtime} to let the RTC start
at the current
UTC or local time, respectively. @code{localtime} is required for correct date
in
-MS-DOS or Windows. To start at a specific point in time, provide @var{date} in
the
+MS-DOS or Windows. To start at a specific point in time, provide
@var{datetime} in the
format @code{2006-06-17T16:01:21} or @code{2006-06-17}. The default base is
UTC.
By default the RTC is driven by the host system time. This allows using of the
RTC as accurate reference clock inside the guest, specifically if the host
time is smoothly following an accurate external reference clock, e.g. via NTP.
If you want to isolate the guest time from the host, you can set @option{clock}
-to @code{rt} instead. To even prevent it from progressing during suspension,
-you can set it to @code{vm}.
+to @code{rt} instead, which provides host monotonic clock if host support it.
+To even prevent it from progressing during suspension, you can set it to
address@hidden (virtual clock). Virtual clock is the clock seen by guest,
+In icount mode of emulation its (long term) speed will be different from
+any host clock, when icount configured to non-auto value or virtual cpu
sleeping
+is off, and no synchronization algorithm is active.
Enable @option{driftfix} (i386 targets only) if you experience time drift
problems,
specifically with Windows' ACPI HAL. This option will try to figure out how
--
2.7.4
- [Qemu-devel] [PATCH 0/4] Fix and improve core RTC function and documentation, Artem Pisarenko, 2018/10/11
- [Qemu-devel] [PATCH 1/4] vl: improve/fix documentation related to RTC function,
Artem Pisarenko <=
- [Qemu-devel] [PATCH 2/4] vl: refactor -rtc option references, Artem Pisarenko, 2018/10/11
- [Qemu-devel] [PATCH 3/4] Fixes RTC bug with base datetime shifts in clock=vm, Artem Pisarenko, 2018/10/11
- [Qemu-devel] [PATCH 4/4] vl, qapi: offset value calculation in RTC_CHANGE event reverted to match behavior before #1797033 bugfix and documented, Artem Pisarenko, 2018/10/11
- Re: [Qemu-devel] [PATCH 0/4] Fix and improve core RTC function and documentation, Artem Pisarenko, 2018/10/17