compiler does show only character position, not the line number
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Yes, by default it shows you the character position, because it's faster to go to character position in vim
:goto number

In case you still want to use line numbers then pass -l option to voc

voc -ls m.Mod

compilation crashes on ARM or Raspberry Pi with recent (like 3.12) kernels.
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> echo 1 > /proc/sys/vm/legacy_va_layout

should fix that.