[syslinux] Syslinux LUA -- output not visible in UEFI mode?

Ady Ady ady-sf at hotmail.com
Sat Apr 6 00:59:52 PDT 2019

> 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 

_ 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.


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