Re: Trouble with running cygwin dll on Vortex86MX+ CPU

["Yaakov (Cygwin/X)" <yselkowitz@users.sourceforge.net>]

On 2014-04-02 18:03, Colin wrote:
> The problem I have can be reduced to this: I compile a simple "Hello
> World" console mode c program. I copy the .exe file and cygwin1.dll onto
> an embedded PC, open a console window, and run the program. The program
> runs, and returns immediately to the command prompt, with no output. No
> error messages, no nothing...
>
> The embedded PC is currently running a full installation of Windows XP
> Professional, SP3. It does so quite happily. It's CPU is DM&P Vortex86MX+
> 933MHz. I am able to run a "Hello World" program compiled with a native
> Windows compiler on it successfully.
>
> In discussing this with the embedded PC supplier, he suggests that the
> cygwin1.dll is exiting because it doesn't recognise the CPU.

Actually, if Wikipedia[1] is correct (yes, yes, I know), the problem is 
that the CPU doesn't recognize the code.  Apparently, these CPUs are 
missing the CMOV instruction used when compiling with gcc -march=i686, 
which has been the default setting for the Cygwin x86 compilers for 
several years now.

Therefore, in order to even attempt to make this work, you would have to 
recompile gcc for -march=i586 default, then rebuild *everything* with 
that gcc; but I can't guarantee that there won't be other issues as well.


Yaakov

[1] https://en.wikipedia.org/wiki/Vortex86#CPU


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