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>
- Don't include paramtree.h in siminterface.h to get rid of duplicates
in a lot of Makefile dependency lines.
- Regenerated Makefile dependencies in iodev and affected subdirectories.
- FIXME #1: including debug.h causes duplicate entries of config.h and osdep.h.
- FIXME #2: cpudb.h appears in most of the iodev* dependencies, but only needed
by config.cc and the cpu class.
- Created framework based on our I/O APIC code and ported HPET core from Qemu
with some required changes for the Bochs timer and IRQ handling.
- Enabled HPET-specific code in the ACPI and rombios32 sources and generated
new ACPI table with iasl.
- The HPET device plugin is now always loaded if the i440FX chipset is selected
(same as ACPI). We have to rethink this when we have implemented a more
modern chipset.
- TODO: Rewrite of the virtual timer code for nanosecond support to make the
realtime synchronization possible with HPET.
- added Android case to the configure script.
- renamed file memory.h to memory-bochs.h to fix conflict with NDK.
- fixed Android issues in some files.
- Implemented wave output using the 'soundfile' driver including dual wave
output in wavemode 3. Removed now obsolete output file handling and other
cleanups. The wave input (recording) feature is not affected by the
wavemode setting.
- Moved VOC file handling to the soundfile code.
- Updated iodev makefile dependencies.
- embedding combined manifest makes BOCHS.EXE usable
- list of DLL plugins now depends on the pci and debugger options
- 'make clean' now removes the generated manifest files
- renamed variable for external rules
- documentation update
complete and usable with the BOCHS.EXE built with the IDE.
TODO #1: fix BOCHS.EXE built with nmake (manifest issue)
TODO #2: make the currently fixed DLL plugin list variable
rules can be built now (keyboard, pit, gameport, serial, vga, svga_cirrus,
hdimage, netmod, soundmod, usb_common). The generated DLLs are usable with the
BOCHS.EXE built with the IDE, but the nmake won't work at all yet.
that is a part of the libtool package. Updated Makefile dependencies.
TODO: check if we can get rid of the ltdl*.* files (this would be possible if
the ltdl library is always available if libtool is present).
- ported Qemu block driver (written by Alex Beregszaszi and Kevin Wolf)
- added helper functions bx_read_image() and bx_write_image()
- TODO: use helper function for the other disk image modes
- added new class bx_vgacore_c containing the core of the standard VGA
emulation. This is now the base class for both vga and cirrus.
- created 2 separate plugins 'vga' (for standard VGA and VBE) and 'svga_cirrus'
(Cirrus emulation). The vga extension option is used to select which plugin
should be loaded.
- TODO: move the pcivga code to the VGA/VBE code, add subdirectory for display
adapters, severak improvements and cleanups
- TODO #1: update MSVC workspace files
- TODO #2: these 'device classes' could be moved to subdirectories, too:
- pci (when we have more than one chipset)
- display (when we have one more device and vga / cirrus cleaned up)
- TODO: add save/restore support, use Bochs function for host to little endian
data conversion, timers of networking modules 'vnet' and 'slirp' should use
the device speed instead of fixed 10 MBit
and the supported ethernet modules
- renamed eth.* files to netmod.*
- pseudo-device plugin implementation similar to 'soundmod'
- TODO: move sound, net and usb stuff to a separate subdirectory of iodev
duplicate log prefixes on Windows if both IDE and USB cdroms are used in plugin mode. Windows also
requires the cdrom base class and the init_cdrom() method to link and work correctly.
DAC2 is sent to the lowlevel sound module. DAC1 and sound input (ADC) are not
yet supported. Also unsupported: CODEC (mixer), UART (MIDI) and legacy support.
Sound module selection in configure script now no longer depends on SB16 and
uses autodetection only.
- fixed segfault when saving bochsrc
