[Vm-dev] VM debugging - breakpoint issue on Windows

[Eliot Miranda]

Hi Vincent,

On Thu, Apr 19, 2018 at 11:27 AM, Eliot Miranda <eliot.miranda at gmail.com>
wrote:

> Hi Vincent,
>
> On Thu, Apr 19, 2018 at 9:30 AM, <Vincent.Blondeau at lamresearch.com> wrote:
>
>>
>> Hi Dave,
>>
>> The optimization options are already disabled in the debug build and
>> -ggdb2 is used. So, the real code is used.
>>
>> How do I change the build in a way that the plugin is external?
>>
>
> I see the same issue as you.  I'll take a look.
>

Something I find strange is TOOLPREFIX:=i686-w64-mingw32-.  I would have
expected  TOOLPREFIX:=i686-w32-mingw32-. Nicolas, have you looked at this
recently?

Vincent, if you try compiling a Hello World and setting breakpoint in main
you should be able to reproduce the issue.  Then you can try different
compilers quickly.  I tried debugging the VM and putting a breakpoint in
parseVMArgs, which is called to parse the command line.  It fails also.  So
we have a problem :-(


>
>>
>> Any experience is always welcome! Thanks!
>>
>> Vincent
>>
>>
>> -----Original Message-----
>> From: Vm-dev [mailto:vm-dev-bounces at lists.squeakfoundation.org] On
>> Behalf Of David T. Lewis
>> Sent: Wednesday, April 18, 2018 17:35
>> To: Open Smalltalk Virtual Machine Development Discussion <
>> vm-dev at lists.squeakfoundation.org>
>> Subject: Re: [Vm-dev] VM debugging - breakpoint issue on Windows
>>
>>
>> Hi Vincent,
>>
>> I am not a Windows user so this may be completely wrong, but one thing I
>> have found in debugging plugins on Linux is that it is often necessary to
>> compile with optimization turned off so that the debugger is dealing with
>> the "real" code.
>>
>> I am guessing that perhaps your debugger is trying to use the C source
>> code to locate something that got optimized away by the compiler.
>>
>> Sometimes it is helpful to compile the plugin as an external plugin (a
>> DLL). You can compile it with zero optimization and compiler flags set (-O0
>> -g or similar), and the resulting plugun should be visible to the debugger.
>> The plugin that you compile this way should work with any VM (optimized or
>> not) and the debugger should still be able to see it.
>>
>> I have not done this on Windows, but that is my experience on Linux so
>> maybe it will help.
>>
>> Dave
>>
>>
>> On Wed, Apr 18, 2018 at 06:33:12PM +0000, Vincent.Blondeau at lamresearch.c
>> om wrote:
>> >
>> > Hi,
>> >
>> > I would like to set up a breakpoint in the VM but I got this error when
>> running:
>> > Cannot insert breakpoint 1.
>> > Error accessing memory address 0x509cad: Input/output error.
>> >
>> > For this, I am using gdb under Cygwin (same issue with powershell) and
>> invoque the primitive I want to test:
>> > pharo.cog.spur/builddbg/vm $  gdb --args ./Pharo.exe -headless
>> ../..somewhereOnMyDisk.../Pharo.image eval "FilePluginPrims new
>> primitiveStdioDescriptorIsATTY."
>> >
>> > I get these results:
>> > GNU gdb (GDB) 7.6.1
>> > Reading symbols from C:\Users\BlondVi\Documents\Git
>> Repos\opensmalltalk-vm\build.win32x86\pharo.cog.spur\buildd
>> bg\vm\Pharo.exe...done.
>> >
>> > Next, I set a breakpoint in the primitive C method I created and run
>> the app:
>> >
>> > (gdb) br sqStdioDescriptorIsATTY
>> > Breakpoint 1 at 0x509cb6: file ../../platforms/win32/plugins/FilePlugin/sqWin32FilePrims.c,
>> line 337.
>> > (gdb) r
>> > Starting program: C:\Users\BlondVi\Documents\Git
>> Repos\opensmalltalk-vm\build.win32x86\pharo.cog.spur\builddbg\vm/./Pharo.exe
>> --headless ../../../../../../../../..temp/logoVM/logoVM.image eval
>> "FilePluginPrims new primitiveStdioDescriptorIsATTY."
>> > [New Thread 27416.0x95bc]
>> > [New Thread 27416.0xa1d0]
>> > [New Thread 27416.0x3aa4]
>> > [New Thread 27416.0x88bc]
>> > (gdb) Warning:
>> > Cannot insert breakpoint 1.
>> > Error accessing memory address 0x509cad: Input/output error.
>> >
>> > What should I do to set the breakpoint correctly?
>> >
>> > Thanks in advance,
>> >
>> > Vincent Blondeau
>> >
>>
>>
>
>
> --
> _,,,^..^,,,_
> best, Eliot
>



-- 
_,,,^..^,,,_
best, Eliot
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