I am trying to make precompiled preambles format with lualatex and mylatexformat package. I'd like to have it in a Fmt/ subdirectory of the working directory. Trying this command line
luatex -initialize --output-directory=Fmt --job-name=mainfile-luaLaTeX &lualatex mylatexformat.ltx mainfile.tex
indeed produces a mainfile-luaLaTeX.fmt — but in mainfile's directory, not in its Fmt/ subdirectory.
However, the similar command lines for xelatex or pdflatex work perfectly. Does anyone know the reason for this, or did I not understand something about lualatex ? Or maybe there is some kind of incompatibility between lualatex and mylatexformat ? Any help solving this problem will be really appreciated.