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

[Eliot Miranda]

Hi Vincent,


> On Apr 18, 2018, at 11:33 AM, <Vincent.Blondeau at lamresearch.com> <Vincent.Blondeau at lamresearch.com> 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\GitRepos\opensmalltalk-vm\build.win32x86\pharo.cog.spur\builddbg\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\GitRepos\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?

AFAICT you're doing everything right.  But if you're on 64-bit Cygwin then it won't work.  You can build the 32-bit vm on a 64-bit windows but gdb can only be used to debug 64-bit programs.  Even installing the gdb from 32-bit Cygwin doesn't work.  So if this is your configuration you'll have the create a 32-but Cygwin and debug the 32-bit app there-on.

HTH

>  
> Thanks in advance,
>  
> Vincent Blondeau
>  
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