[syslinux] Debug C32 Module

[Johann Obermayr]

Hello,

> -----Ursprüngliche Nachricht-----
> Von: Syslinux <syslinux-bounces at syslinux.org> Im Auftrag von Ady Ady via
> Syslinux
> Gesendet: Freitag, 24. Mai 2019 16:56
> An: syslinux at syslinux.org
> Betreff: Re: [syslinux] Debug C32 Module
> 
> > we have wrote a own C32 module, loaded with "DEFAULT mod.c32"
> >
> > But sometime the module mod.32 are not loaded & started.
> > How we can debug this ?
> > Or give some debug output.
> > In the main of the module there is a printf, but the text are not
> > shown at booting.
> 
> 
> If you are building the binaries by yourself, then nobody really knows where
> the problem could be, considering that even the current git master head fails
> for UEFI mode.
> 
> If you are using some package from some distro, or perhaps upstream 6.04-
> pre1, please include such details in the future.
> 
> Yours would not be the first report about display problems when using
> syslinux.efi. One such report (among others) is about lua.c32, also failing to
> correctly display output text; the "output" is there, but it cannot be
> seen/read.
> 
> Having said that, at least one test could be performed anyway, just in case.
> 
> Instead of using:
> 
> ###
> DEFAULT mod.c32
> ###
> 
> 
> please try:
> 
> ###
> DEFAULT modlabel
> PROMPT 1
> 
> LABEL modlabel
> COM32 mod.c32
> ###

I will look to change this.

> 
> The point is to use a label for the DEFAULT directive, instead of a non-label
> command.
> 
> With this minimal cfg file, When you boot you should at least get to the
> Syslinux "boot" prompt. At that point, press [ENTER] in order to execute the
> default label.
> 
> Probably the result won't change from your previous test, but at least you
> will be able to discard the potential problem in the DEFAULT directive.
> 
> Other than that, _perhaps_ the following might help someone with the
> relevant skills (although, please note that the whole page is rather outdated
> and possibly not very much relevant for UEFI, but YMMV):
> 
> 
> syslinux.org/wiki/index.php/Development/Debugging#Syslinux_Dynamic_D
> ebug
> ger

Thanks.

> 
> Regards,
> Ady.
> 
> 
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I have found my problem.
It was an old entry "DISPLAY  some_filename"
Without exist file with this name. Than the module crash (sometime, not always)
Now I have remove the DISPLAY entry and looks good.

Thanks
  Johann