- Using the special value of 0 enables this feature. In that case the vertical
frequency is used for the display updates. The update() method is called at
the "vertical retrace end" time and sets the time of the display start. This
value is used to set the vertical retrace indicator in VGA register 0x03da.
- This feature is not yet enabled if Voodoo support is present. The Voodoo device
has it's own vertical timer and needs some more testing and possibly some changes.
- Increase buffer size and allocate buffer dynamicly.
- Make sure the beep_level is correctly set up in dsp_generator().
- TODO: fix timer code for usable sound output with the speaker.
Temporarily disable fifo_reset() in recompute_video_memory(). FIFO handling must
be observed and a better solution must be found.
Fixed hang after pressing power button: destructor modification was required since
the swapbuffer command can depend on vertical retrace.
Removed disabled BX_DEBUG code and VGA_TRACE_FEATURE symbol.
Some other small fixes and cleanups.
TODO #1: review MAP13 addressing in case start address > 0.
TODO #2: review chain4 code in medm_write().
- Fixes in MAP13 disabled mode (VGA mode 6): half dot clock, color support
- Modified method get_vga_pixel(): now using row start address as an argument
- Added CMOS image options to runtime menu (except RTC init).
- Fixed default size of Bochs CMOS RAM (s.max_reg).
- Fixed bochsrc parse to make 'rtc_init' parameter work.
- In textconfig now using SERIES_ASK for CMOS image options.
- Show message box while restoring hardware state.
- Set modeless message box handle to NULL after destroying it.
- Reset all config options to default before restoring config.
- Fixed CMOS RTC value after restore if in 12-hour-mode.
- Fixed possible segfault in the plugins code caused by Voodoo plugin in VGA mode
(found at restore code testing).
by Michele Giacomone
Detailed description:
-Observed issues
Due to some limitations only dates between 1980 and 2038 can be
used in a reliable way.
Also, bochs incorrectly assumes a linear correspondence between
the data returned by the <time.h> functions localtime() and
mktime(), and isn't setting the latter properly.
Bochs keeps its internal time value dependent to these functions
after setup, assuming that their internal settings won't change
on the go - which is not the case.
In my OS, and in my timezone, this leads to incorrect startup values
for 5 months each year and unreliable values if the simulation is
kept going for a long time. (a feedback between localtime() and
mktime() is created which keeps shifting back the time)
Also, the RTC simulation is not realistic since the clock fixes
itself across DST changes, without updating any DST related flag,
a behavior that no guest OS expects.
-Proposed fix
This is implemented in such way that no bochs' previous behavior
is changed, a part from the broken ones, with legacy in mind
== the user can keep using bochs exactly as before knowing nothing
of this patch
+Make the internal s.timeval variable a Bit64s, so it can fit all
values that the cmos can correctly represent, reported below:
MIN setting -62167219200 => 0000/01/01 SAT 0:00:00
MAX BCD setting 253402300799 => 9999/12/31 FRI 23:59:59
MAX BIN setting 745690751999 => 25599/12/31 FRI 23:59:59
And then fix each reference to these so it can handle such values
And make bochs correctly wrap around for under/overflows, so that
only the most significant bits of the century are lost.
+Do the same thing to the bochs time0 parameter, so all the above
values can be chosen at startup (despite being now legal values,
1 and 2 will still be treated as "local" and "utc"). Note that
normally only BCD settings are valid since bochs' CMOS defaults
to such operating mode - the only way to use the binary range
is by loading a cmos memory map.
+Make the internal s.timeval variable independent from external
factors. This means providing a small set of time handling
functions, contained in "iodev/utctime.h", which must work in
any environment in which bochs compiles, accessing no external
resource. This also means that after startup, s.timeval will only
be changed internally, and no call to the OS time functions will
be made.
+Make the internal s.timeval variable timezone independent, to
have a linear correlation between its values and valid CMOS
settings. To make it easier, s.timeval is gonna be treated as
if the current timezone was UTC: so,
- if the user selects UTC as time0, s.timeval will become current
time(NULL)
- if the user selects localtime, s.timeval will be computed as
the value which will display the same broken down time as
localtime(&now)
- if the user inputs a time formatted string the proper s.timeval
to displayed will be easily calculated,
- if the user inputs a starting time value, s.timeval will be
computed as the value which will display the same broken down
time as localtime(&user_input) to ensure the same operation as
before.
A "tz=utc" is displayed when bochs prints out the current time
value, to warn users about the difference in meaning between the
internally kept time value and the value they can set through
the "time0=" parameter. This might be changed to communicate
instead the time value they can input to get the same setting,
but performing such calculation (except for the startup time)
suffers from all the mktime()/localtime() problems listed above
so I did not do it.
The range of "time0" is automatically adjusted so all users in
all time zones can set any legal value despite "time0=" having a
local meaning.
A thorough explanation of what I did and why can be found in the
"iodev/utctime.h" library header.
---------
Co-authored-by: Stanislav Shwartsman <sshwarts@users.sourceforge.net>
Co-authored-by: Volker Ruppert <Volker.Ruppert@t-online.de>
