Syslinux - Apr 2019 - Syslinux LUA -- output not visible in UEFI mode?

Hello all,

We're having the following issue: when in UEFI mode,
any output/errors from a lua script is invisible!

This occurs even just running 'lua -v'.  It runs and returns to
a (visible) 'boot:' prompt, but there is simply no output visible
from lua!  (It does do a linefeed, but no visible text appears.)

Has anyone encountered this? And/or know of a solution?

For reference, I'm using a Dell Optiplex 7040 at my test platform.

Thanks,
WRSomsky

-- 
Dr. William R. Somsky           	                   somsky at uw.edu
Department of Physics, Box 351560		 B217 Physics-Astro Bldg
Univ. of Washington, Seattle WA 98195-1560		    206-616-2954

> We're having the following issue: when in UEFI mode,
> any output/errors from a lua script is invisible!
> 
> This occurs even just running 'lua -v'.  It runs and returns to
> a (visible) 'boot:' prompt, but there is simply no output visible
> from lua!  (It does do a linefeed, but no visible text appears.)
 
 
Yes, the report can be confirmed.

FWIW, the invisible output is not just a linefeed; rather, the "same"
output
that would be expected is not seen.

To replicate, from a boot prompt using 6.04-pre1 in _BIOS_ mode:

_ the output of 'lua.c32 -v' (in lower-case) is correctly shown, in one 
line/row;

_ the output of 'lua.c32 -V' (in upper-case) is correctly shown,
spanning
several lines/rows.

Repeating the above 2 commands in UEFI mode (with the corresponding _UEFI_ 
binaries) shows the same amount of lines/rows (respectively) in between
"boot:"
prompts, but the text is not seen.

I don't know whether this is about some background/foreground output colors,
or
somewhat related to the problems with "clear screen" methods under
UEFI mode
(which show similar unwanted behaviors), or specific to lua.c32.

Regards,
Ady.

I've been looking at this issue again, and I've found that it has
something to do with the functionality invoked by the openconsole()
call.

I find if I create and compile the file com32/modules/no.c:

  #include <stdio.h>
  #include <console.h>
  int main(int argc, char *argv[])
  {
  openconsole(&dev_null_r, &dev_stdcon_w);
  fprintf(stdout, "STDOUT...\n");
  fprintf(stderr, "STDERR...\n");
  }

I get the "invisible text" behavior under UEFI. However, if I comment
out
the 'openconsole' line, it works fine.  (I got this from comparing cat.c
and ifmemdsk.c, as the former has visible text, and the latter doesn't.)

Similarly, if I comment out the 'openconsole' line w/in
com32/lua/src/lua.c,
lua.c32 then seem to behave as expected, and all text is visible, at least to
a casual perusal.

Unfortunately, I don't know what all 'openconsole' does behind the
scenes, so I don't know if omitting that call breaks some other
needed functionality. (Possibly needed for BIOS behavior or on some
other systems?)

- WRSomsky


On Sat, Apr 06, 2019 at 07:59:52AM +0000, Ady Ady via Syslinux
wrote:
> > We're having the following issue: when in UEFI mode,
> > any output/errors from a lua script is invisible!
> > 
> > This occurs even just running 'lua -v'.  It runs and returns
to
> > a (visible) 'boot:' prompt, but there is simply no output
visible
> > from lua!  (It does do a linefeed, but no visible text appears.)
>  
>  
> Yes, the report can be confirmed.
> 
> FWIW, the invisible output is not just a linefeed; rather, the
"same" output
> that would be expected is not seen.
> 
> To replicate, from a boot prompt using 6.04-pre1 in _BIOS_ mode:
> 
> _ the output of 'lua.c32 -v' (in lower-case) is correctly shown, in
one
> line/row;
> 
> _ the output of 'lua.c32 -V' (in upper-case) is correctly shown,
spanning
> several lines/rows.
> 
> Repeating the above 2 commands in UEFI mode (with the corresponding _UEFI_ 
> binaries) shows the same amount of lines/rows (respectively) in between
"boot:"
> prompts, but the text is not seen.
> 
> I don't know whether this is about some background/foreground output
colors, or
> somewhat related to the problems with "clear screen" methods
under UEFI mode
> (which show similar unwanted behaviors), or specific to lua.c32.
> 
> Regards,
> Ady.
> 
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-- 
Dr. William R. Somsky           	                   somsky at uw.edu
Department of Physics, Box 351560		    B217 Phys-Astro Bldg
Univ. of Washington, Seattle WA 98195-1560		    206-616-2954