parameter so we know which source modules are requesting
timers. Also added a SpewPeriodicTimerInfo #define in
case somebody is still having guest OS hang problems. If
enabled, this macro will force a brief dump of the active timers
list to the bochsout.txt file, every 5Million ticks.
If the lowest timer's period is extremely low, that would be
suspect.
requesting source can be registered as well. Otherwise, there
is no way to know which source modules are requesting
suspect frequencies which are too high.
instead of winmm being a part of GUI_LINK_OPTS_WIN32 only, it is
placed in @DEVICE_LINE_OPTS@ so that it will be used for sdl, rfb, wx,
etc.
- solve compile problems when building bximage, niclist, and any other
console based program. The compile flags returned by wx-config and
sdl-config did strange things to these console programs, for example
redefining main to SDL_main. Because I wanted to use the
configure-generated CFLAGS to compile the programs, but I wanted to
avoid including GUI specific compile options, I split up the configure's
@CFLAGS@ variable into @CFLAGS@ and @GUI_CFLAGS@, and split
@CXXFLAGS@ into @CXXFLAGS@ and @GUI_CXXFLAGS@. All programs in the
Bochs binary will use both, but the console programs will just use
@CFLAGS@ or @CXXFLAGS@.
- gui/Makefile.in, I no longer use the gui specific CFLAGS variables,
SDL_CFLAGS and WX_CXXFLAGS. These values are included in CFLAGS and
CXXFLAGS now.
- modified: configure.in, configure, all Makefile.in's
Include SDL.h so that the C language prototype can be found. Otherwise
SDL_main() will get its name mangled and not match what the SDL library is
expecting.
testing. Please try these out if you want to help test
them or if your guest OS appears to be hanging with
no apparent activity. The old bochs internal timer
framework is broken in several areas.
I put these in the patches directory for now. After
a 'make all-clean', you can do something like:
mv pc_system.cc pc_system.cc-old
mv pc_system.h pc_system.h-old
cp patches/pc_system.cc-kpl .
cp patches/pc_system.h-kpl .
make
And let me know if A) they work for you and B) if they help
the hanging problem.
restart another one in wxWindows. Fixed that. Also, on restart, the
apic id's left over from the first run were causing panics. Fixed that.
- modified: main.cc cpu/apic.cc cpu/cpu.h cpu/init.cc
up pc_system.h. Moved all variables under the private: section,
as well as a few member functions. The string instructions
were accessing a field directly (only reads), so I indirected
that via an inline member function for better abstraction.
"-pthread" flag to the link line, but as of wxWindows 2.3.3 their
wx-config script adds it for us. Given the keyboard mapping improvements
in wx 2.3.3, I don't expect to support any previous version.
To: bochs-developers@lists.sourceforge.net
Subject: [Bochs-developers] Fix for configure.in bug
This patches fixes a bug in configure.in which prevents configure from setting
default values for CFLAGS and CXXFLAGS. Normally, the way autoconf builds
configure, it will set default values for CFLAGS and CXXFLAGS of `-g -O2'.
But, if the user specified them (via the environment), it won't touch them.
The clause in configure.in that tries to set platform-specific flags breaks
this because it always assigns a value (usually blank for most platforms),
which fools the defaulting mechanism later on.
all available optimizations in one shot.
Finished one last case of an instruction which could but didn't use
the Read-Modify-Write variants of access.cc functions.
Started going through the integer instructions, merging obvious cases
where there are two "if (modrm==11b) {" clauses and very little
action in between, and cleaning up the aweful indentation leftover
from many years ago when those instructions were implemented using
cut-and-paste. We may get a little extra performance out of these
mods, but they'll also be easier after I'm finished to enhance
with asm() statements to knock out the lazy flags processing on x86.
now simply return a cached value which is set upon mode changes.
The biggest problem was protected_mode() which did something like:
return CR0.PM && ! EFLAGS.VM
This adds up when it was being executed many times in branch functions
etc. Now, cached values are set and sampled instead.
- parallel port detection fixed:
* write the value of AX to 0x0410, not BX
* the timeout value is a byte and now stored in CL
* the offset of the port address list is 2 bytes
Used patch.disasm to do
1) clean up the disasm output to make the dispaly of extra stuff optional.
2) included the part of the patch which displays displacements as
proper addresses.
and Jas Sandys-Lumsdaine to split out common instructions into
variants which deal with the mod=11b case (Reg-Reg) and the
other cases (which do memory ops). Actually, I only split
MOV_GwEw and MOV_GdEd for now. According to some instrumentation
of a Win95 boot, they were the most frequently used opcode by far.
Essentially, when I coded a few of the instructions to use
asm()s for acceleration of the eflags, I got lazy and only
used the asm() to compute eflags and let the normal C operation
do the actual operation. Jas's patch, moved the asm()s such
that they now do the work of the operation as well.
The patches look great. The code reads a lot better as well.
Further work can be done to give the compiler more options with
register scheduling.
were simply replacements of the eflags mask constants with
the macro names already in cpu.h for asm() statements. I forgot
to use the macros for some instructions.
0x000008d5 -> EFlagsOSZAPCMask
0x000008d4 -> EFlagsOSZAPMask
Some things changed in the ctrl_xfer*.cc, fetchdecode*.cc,
and cpu.cc since the original patches, so I did some patch
integration by hand. Check the placement of the
macros BX_INSTR_FETCH_DECODE_COMPLETED() and BX_INSTR_OPCODE()
in cpu.cc to make sure I go them right. Also, I changed the
parameters to BX_INSTR_OPCODE() to update them to the new code.
I put some comments before each of these to help determine if
the placement is right.
These macros are only compiled in if you are gathering instrumentation
data from bochs, so they shouldn't effect others.
just the wxwindows ones. This is required on cygwin, for example, because
the CFLAGS and CXXFLAGS include gcc flags that change code generation:
-fno-pcc-struct-return and -fvtable-thunks. It is not safe to mix code
compiled with these flags with code compiled without. I learned this the
hard way when I found that sometimes code that called a virtual member
function was jumping to the WRONG member function.
Created 64-bit versions of some branch instructions and
changed fetchdecode64.cc to use them instead. This keeps the
#ifdef pollution down for 32-bit code and made fixing them
easier. They needed to clear the upper bits of RIP for
16-bit operand sizes. They also should not have had a protection
limit check in them, especially since that field is still
32-bit in cpu.h, so there's no way to set nominal 64-bit values.
The 32-bit versions were also not honoring the upper 32-bits
of RIP.
LOOPNE64_Jb
LOOPE64_Jb
LOOP64_Jb
JCXZ64_Jb
Changed all occurances of JCC_Jw/JCC_Jd in fetchdecode64.cc to
use JCC_Jq, which was coded already. Both JMP_Jq and JCC_Jq are
now fixed w.r.t. 16-bit opsizes and upper RIP bit clearing.
63..16 when a 16-bit operand size JMP is executed. Previous
fix cleared only 63..32. I since realized, this is the case
which does parallel the 32-bit semantics.
fetching 64-bit address opcode info, which was incorrect.
Fixed. Got rid of BxImmediate_Oq. fetchdecode64.cc now
uses BxImmediateO, like the fetch routine does. Addresses which
are embedded in the opcode, have a size which depends on
the current addressing size. For long-mode, this is
either 64 (default) or 32 (AddrSize over-ride). BxImmediate_O
now conditionally fetches based on AddrSize.
64-bit bug#2: In JMP_Jq(), when the current operand size is
16-bits, the upper dword of RIP was not being cleared. The
semantics with this case are weird - one would think the
top 48 bits would be cleared, but apparently only the top
32 bits are. Anyways, I fixed this.
Replaced some of the messy immediate fetching (byte-by-byte) in
fetchdecode64.cc with ReadHost{Q,D}WordFromLittleEndian() calls
for cleanliness. Should do this for all the cases, plus
the 32-bit stuff.
conditionally include <windows.h>. This may seem like a drastic step
for just one little type, but I expect before long we may want to use
other symbols like VK_F12 which are also in windows.h. In a cygwin
compile this is required.
wxWindows guis.
- if cross configuring, don't insist on finding curses library.
- on normal configures, when the target platform is win32 (windows, cygwin,
mingw), don't insist on finding pthread either.
(I'm starting to wonder if when cross_configure=1 we shouldn't just skip over
ALL of the library and header checks. When you're going to configure on one
platform and build on another, all that information is useless anyway.)
on the wxWindows interface. There are many more changes here than
absolutely required to fix the memory leaks. Instead, I've tried to
clean things up so that it does the right thing, and is easier to
read and maintain.
- For events that the text mode interface is going to ignore anyway, I #ifdefed
the event creation code instead of calling new and then delete.
- now all synchronous events in siminterface.cc are created as local variables
on the stack. Some of them were allocated with new before, and yes some of
them leaked.
- now I ignore the result of sim_to_ci_event (&event). It was always
returning a pointer to the input event anyway. This makes the event
sending code simpler.
- wxmain.cc:
- in the BxEvent handling functions, now all cases "break" down to common
code at the end which deletes async events. This is easier to read than
having each case handle the delete individually.
- in OnLogMsg, do not delete the event here because it is now handled
in the common code of OnSim2CIEvent instead.
- thanks to Christophe for pointing out the location of the worst
memory leak.
- make bx_init_main return -1 if any parse errors occur.
- wxWindows: if bx_init_main returns -1, don't even show the application
window. You'll get an error dialog and then it exits. So far this
only happens if you run with -q and the parse fails.
- non-wxWindows: if bx_init_main returns -1, just exit. So far this
only happens if you run with -q and the parse fails.
- with these changes, handling of bochsrc parse errors seems to work
as you would expect. And it certainly doesn't go into an infinite
recursive loop, as it used to!
- a little more testing and I can close
bug 614175: infinite panic loop if bochsrc buggy
- modified: main.cc gui/siminterface.h gui/wxmain.cc
and into wxmain.cc, like other actions.
- set a default siminterface callback for the whole application, which is used
whenever the simulator is not running. This is important when the wx code
calls simulator or param code and triggers a BX_PANIC or something.
The default callback is responsible for displaying error messages which
appear while reading the bochsrc, for example.
- move the implementation of BX_SYNC_EVT_LOG_ASK and BX_ASYNC_EVT_LOG_MSG
into a separate function OnLogMsg(). In the future, OnLogMsg() may be called
from the application default callback on errors.
- modified: gui/wx.cc gui/wxmain.cc gui/wxmain.h
wx behavior worked out, I'll take out the ifdef and settle on something.
- use new enums BX_LOG_ASK_CHOICE_CONTINUE, BX_LOG_ASK_CHOICE_DIE, etc.
- do not use BX_PANIC inside fatal function! it is very likely to reenter,
causing infinite recursion. Use fprintf instead.
(0=success, -1=failure). If parse_line_unformatted returns failure, I
stop parsing the bochsrc.
- implement all parsing BX_PANICs with new PARSE_ERR macro, so that we can
easily change the behavior of all parse errors at once. For now, I want
it to BX_PANIC and then return -1 (case panic continues). Eventually I
might turn it into BX_ERROR and return -1.
- moved cpu_online_map into the BX_CPU_C structure as a static member
(there is only one per bochs, not one per CPU)
- reduced the diffs in several places to make it more clear what had changed
- removed lots of whitespace diffs
Since the SYSCALL replaces the LOADALL instruction, it is incompatible with
earlier CPU types.
At moment, the SYSCALL is only enabled by x86-64 emulation, but the code
can be incorporated in IA32 only emulations.
Instructions added:
0F 05 SYSCALL (replaces LOADALL)
0F 07 SYSRET (new)
TODO: restructure #if ... so that it can be used by non x86-64 emulations.
smarter. If you use --enable-x86-64, it has the following side
effects on other options:
- cpu level defaults to 6 instead of 5
- ignore bad msr defaults to on (Peter T. requested this)
- if cpu level is 6 or greater, these options are enabled by default.
- 4meg pages (PSE)
- physical address extensions (PAE)
- global pages (PGE)
- apic support
- a few weeks ago I changed the gui code so that it always made a copy
of the clipboard data using new Bit8u[] and passed it into the keyboard
code. But I didn't get the keyboard code quite right, and Christophe
noticed the incorrect malloc that I had forgotten to remove. I changed
it to work as I intended:
1. gui code allocates paste buffer (new), copies clipboard data in
2. gui code passes the buffer to the keyboard code, and forgets about it
3. keyboard code uses the buffer, then frees it when finished (delete)
- modified: iodev/keyboard.h iodev/keyboard.cc
. 4 ata interfaces support
. devices auto-detection
. 16bits/32bits device access
. EDD3.0 support
. ata/atapi layer rewrite
. added verious DEBUG_XXX to debug only parts of the bios, because we're running low on data space in debug mode
. moved ata data at offset 0x121 in EBDA. Previously, data was being overwritten by keyboard.sys
. added jump to [0x40:0x67] after reset if shutdown status is 0x05. Fixes bug [ 601166 ] CMOS Problem @ "0x0F Index 0x05 data"
. DMA controller init on POST entry
configuring for a different machine. This is used to short-circuit
certain sanity checks, such as existence of certain required libraries.
- in --with-wx configuration, when $cross_configure=1, do not abort
configure if library is not found.
- if wxWindows version not found, print "not_found" instead of nothing
From his patch file text:
> This patch adds Promise DC2300 VLB IDE Support.
> You may find msdos and win95 drivers on the net. Look for
> P2300W95.ZIP and DC2300VLBIDEver260b.ZIP.
>
> The good news is that now win95 natively sees my cdrom,
> and that the disks are not in msdos compatibility mode any more.
>
> The bad news is that it works only for the first ata interface.
>
> I tested that patch on msdos and win95 only.
>
> Some info on VLB IDE can be found at http://ryston.cz/petr/vlb/
I got Win95 running with 32-bit paging/filesystem using the
recommended driver and these patches. Since the patches did
such a good job bracketing code modifications with a #define,
they might as well become part of the current CVS code.
use getB_CF() etc. getB_CF() and friends are only for a relatively
small number of cases where a true boolean/binary number (0 or 1) is required
rather than 0 or non-0 as is returned by get_CF().
loadSRegLMNominal() which should be used to load a segment register
in long-mode with nominal values which are compatible with existing
checks and expectations for descriptor cache values.
Fixed 64-bit iret to not do a descriptor fetch if SS selector is null.
Also load SS with loadSRegLMNorminal() in the same case.
was not correct (used == 0, rather than s&0xffc == 0). Also,
with a null SS selector, it was fetching the descriptor anyways.
Put more code inside the if (selector != NULL) clause.
For a temporary measure I added the local INIT_64_DESCRIPTOR
from segment_ctrl_pro.cc, and used it in the case that the
SS selector is null. We need to make a real function which
sets a descriptor in long-mode to nominal values. I'm going
to do that next... I can't stand seeing the current hacks. :^)
section title, and less like the grammar that you're supposed to use.
Someone on irc was confused because it was written in uppercase, but then
bochs did not accept the uppercase ATA0-MASTER parameter.
Fixed/updated/cleaned guest2host TLB speedups for Long mode.
I now can boot the Linux x86-64 kernel to the VFS mount message,
using all the accelerations.
these from interfering from a normal compile here's what I did.
In config.h.in (which will generate config.h after a configure),
I added a #define called KPL64Hacks:
#define KPL64Hacks
*After* running configure, you must set this by hand. It will
default to off, so you won't get my hacks in a normal compile.
This will go away soon. There is also a macro just after that
called BailBigRSP(). You don't need to enabled that, but you
can. In many of the instructions which seemed like they could
be hit by the fetchdecode64() process, but which also touched
EIP/ESP, I inserted a macro. Usually this macro expands to nothing.
If you like, you can enabled it, and it will panic if it finds
the upper bits of RIP/RSP set. This helped me find bugs.
Also, I cleaned up the emulation in ctrl_xfer{8,16,32}.cc.
There were some really old legacy code snippets which directly
accessed operands on the stack with access_linear. Lots of
ugly code instead of just pop_32() etc. Cleaning those up,
minimized the number of instructions which directly manipulate
the stack pointer, which should help in refining 64-bit support.
user can turn on/off use of native host specific inline asm
statements. By default, this option is enabled, so you only
need it to disable inline asms in your compile for now.
Currently only on x86+GCC environments, will inline asm()
statements be used. Eventually, other platforms could specify
some asm()s; probably for endian issues such as byte-swapping
and unaligned memory accesses. On x86, there are some inline
asm()s which do the arithmetic EFLAGS processing so that the
lazy flags handling is somewhat bypassed. Eventually, I'll
add more, at least for the more common instructions. This
adds a little extra performance.
giving it Bit32u pointers. On MacOSX for some reason Boolean is set to
unsigned char instead of unsigned int, so it actually cares that we get the
type right.
- return model=2 so that Linux recognizes the processor as having an APIC.
We don't really know what Hammer returns.
- in SetCR4, allow bits 9 and 10 to be written
- added jump to [0x40:0x67] after reset if shutdown status is 0x05. Fixes bug [ 601166 ] CMOS Problem @ "0x0F Index 0x05 data"
- changed various occurences of "mov ax, #0000" by "xor ax, ax"
- fixed serious bugs in EDD function 0x48
- included Volker's rombios recent changes to PCIBIOS
- initialization of DMA controller on POST entry
The function gets the real time in useconds and puts it in
a Bit64u. This function is defined when:
BX_HAVE_REALTIME_USEC is 1.
Right now, BX_HAVE_REALTIME_USEC is defined to be BX_HAVE_GETTIMEOFDAY
and bx_get_realtime64_usec is defined in terms of gettimeofday().
However, it could be defined in terms of any other method of obtaining
the current time accurate to the usecond. That is why I moved the
function to osdep and added the new define.
the icache pageStamp check too early, before it was known
that the TLB entry would produce a physical address in
range of the normal part of physical memory. PCI accesses
were causing seg faults because of this. I haven't tested
this for PCI.
- Features :
. number of active channels defined at boot-time config
. new options in bochsrc
. up to 8 devices support (disks or cdroms)
. up to 4 cdrom devices can be changed at runtime config
. wxwindows config interface
which says to paste getB_ with flag and then paste with (. It should
be "getB_##flag(void)". Some preprocessors are complaining about pasting
the symbol with the paren.
of (1 & (val32>>N)), and added a getB_?F() accessor for special
cases which need a strict binary value (exactly 0 or 1). Most
code only needed a value for logical comparison. I modified the
special cases which do need a binary number for shifting and
comparison between flags, to use the special getB_?F() accessor.
Cleaned up memory.cc functions a little, now that all accesses
are within a single page.
Fixed a (not very likely encountered) bug in fetchdecode.cc (and
fetchdecode64.cc) where a 2-byte opcode starting with a prefix
starts at the last offset on a page. There were no checks
on the segment overrides for a boundary condition. I added them.
The eflags enhancements added just a tiny bit of performance.
- don't allow MMX on cpu level < 5.
- require FPU support on cpu level >= 55
- don't allow MMX support without FPU support (moved this check from
cpu/i387.h to config.h)
- PacketSetReadTimeout: instead of calling with a very short timeout,
now we call it with -1 which means no timeout.
- Psyon found that Peter Tattam's changes, while necessary for win95, broke
WinNT/2000. So now on Windows NT/2000, we still call
WaitForSingleObject(lpAdapter->ReadEvent,0) but we ignore the return value.
parameter values associated with the dialog and updated the wxWindows
controls. At the time I didn't realize that I was overriding
wxWindow::Refresh() which repaints the window. Later, I renamed the method
to CopyParamToGui() to make it more clear, but many of the callers in
wxmain.cc continued to call Refresh(), which now reverted to the parent class
wxWindow::Refresh(). Since there was no compile error I didn't notice for a
while, but it caused the ParamDialogs to repaint themselves constantly but
never actually change their values. This is now fixed by changing those
method calls to CopyParamToGui().
started using a wxTimer to trigger the redraws. Now instead of calling
MyPanel::OnPaint directly, I call Refresh() instead. This makes the Windows
display work correctly.
I'm not sure why this wasn't needed before, but after switching to
wxWindows 2.3.3 it seems to be important.
- in a wxLogDebug() call I was trying to pass a struct instead of a string.
Fixed that.
- hardcode BX_HAVE_GETTIMEOFDAY=0 if cross compiling for VC++
(this part hasn't been tested)
- modified files: configure configure.in config.h.in iodev/pit_wrap.cc
so frequently.
Coded asm() statements for INC/DEC_ERX() instructions.
Cleaned up the iCache a litle including a bug fix. The
generation ID was decrementing the whole field including
some high meta bits. That could roll over after 1 Billion
cycles. I know only decrement if the field is valid, to
save the write.
I implemented inline functions which can serve the value of
the arithmetic flags if they are cached, and redirect to
the lazy_flags.cc routines if not.
Most of this was just prep work for adding more asm() statements
for native eflags processing when on x86.
'char_changed'. These variables are currently only used by the win32 gui for
the update of the font bitmaps. SDL and wxWindows do not use the variables
since they are using the charmap data directly
- free text snapshot memory when the user has cancelled the dialog
- write text snapshot file in binary mode (disables the LF -> CRLF conversion
in cygwin)
- pci2isa prefix changed to "P2I"
- device name changed to "PIIX3 PCI-to-ISA bridge"
- added more default values to the reset() function
- added stubs for i/o mapped registers
- array pci_conf[] is now a part of the structure s
a precursor to making it a runtime option. I'm not
sure how to do this, but it should be trivial. All it
would take is adding the option and changing the
macro for BX_USE_REALTIME_PIT to point to that option.
also extended by the REX.B field on Hammer) is passed to instructions.
I rearranged the bxInstruction_c to free up a field to be used
to pass this info when mod-rm bytes are not used. This got rid
of the ugly ((i->b1 & 7) + i->rex_b) code.
Probably shaved just a very little run time off Hammer emulation,
and even less on x86-32. The resultant is a little cleaner anyways.
and I could never explain it. The problem was that in keyboard.cc it
included "math.h" with quotes instead of <math.h> with less than/greater
than, so gcc -MM didn't realize it was a system header.
- MyPanel::blankCursor
- MyFrame::panel
- AdvancedLogOptions::action (2d array of wxChoice *'s)
- ParamDialog::idHash, ParamDialog::paramHash, and ParamStructs
- file dialog in BrowseTextCtrl
- fix illegal use of a wxObject. I had been clearing the ParamStruct
with memset(), but I forgot that ParamStruct was a subclass of wxObject
so I was trashing the wxObject fields too! Instead I created a
ParamStruct constructor that clears the pointers to NULL.
- comment out debug output from AdvancedLogOptionsDialog::SetAction
- modified files: gui/wx.cc gui/wxdialog.cc gui/wxdialog.h
gui/wxmain.cc gui/wxmain.h
- put off some log related features until later
- advanced log options and debug log are done, so I removed them from the list
- added some wxWindows coding hints I found on usenet
interface) by using get/set_default_log_action. This has very minimal effect
on the behavior of the text config interface.
- modified: main.cc gui/control.cc
time, so I've tried to improve it. Now the logfunctions class has a
static field default_onoff[] which represents the default actions for
each kind of log message. Default_onoff[] is initialized with static
data so it should be valid by the time it's used. This can be reached by
static accesors logfunctions::set_default_action and
logfunctions::get_default_action. It seemed appropriate to put the defaults
inside the logfunctions class, rather than in bx_options or siminterface.
However, to make them accessible to the config interface, I added similar
methods in siminterface that map to the accessors in logfunctions.
- logio.cc had two different definitions of LOG_THIS for different halves
of the file, which was ugly and confusing. (LOG_THIS is needed for BX_INFO,
BX_DEBUG, etc.) I removed the first definition and fixed the minor compile
problems that ensued. In the initializers for iofunctions, everything
is complicated because of the unpredictable order that constructors get
called. They must use this->log to print things, because genlog hasn't
been initialized yet.
- now if SIM->set_log_action(int mod, int level, int action) is called
with mod<0, it sets the action for all modules/devices instead of just one.
- modified: bochs.h logio.cc main.cc gui/siminterface.cc gui/siminterface.h
- LogOptionsDialog: show the "no change" option. When options other than
"no change" are selected, set both the default log action and the
specific log action for all devices.
- AdvancedLogOptionsDialog: store the wxChoice*'s in a 2d array since I
have to refer to them later.
- since both the log options and advanced log options dialogs needed to
create many wxChoices using similar rules, I moved the creation code
into a utility function makeLogOptionChoiceBox.
- I finally discovered the wxADJUST_MINSIZE option to wxSizer::Add(),
which solves some layout problems that I was having with wxChoices.
With this setting, the wxChoice will automatically grow to the size of
the largest string that can be selected.
- improve sizing of the scrollWin according to the desired size of the panel
that contains all the wxChoices.
- add sketches for proposed dialog that combines both LogOptionsDialog and
AdvancedLogOptionsDialog using tabs
From sf patch page :
This patch adds remote GDB stub capability to Bochs.
It's an updated version of the patched bochs 1.3pre1 in
found in this URL:
http://www.rtmk.org/bochs-gdb.html
more details in the same site. thanks Johan Rydberg
