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I accidentally left off the -j [jobs] when compiling the Qt4 git://gitorious.org/qt/qt.git repository from mingw32-make as per the Building Qt4 documentation. Will this make any other difference beside the amount of time it takes to compile?

My understanding of the command.

  • My understanding of the command is that it controls the amount of jobs being performed but if nothing is set after -j in [jobs] then it may be pointless to have.
  • I could be wrong because I still don’t have a complete understanding of the configure.exe command syntax (eg. configure.exe -opensource -confirm-license -release -xplatform unsupported/blackberry-armv7le-qcc -arch arm -nomake examples nomake demos -no-neon -opengl es2 -prefix c:\dev\qt4install).
Brandon Clark
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  • Not sure I understand the question. make -j, make -j, make -j1, make all must have the same build results, otherwise that'd be a bug. (e.g. make install for qtbase often fails on OS X with -j => bug). – Frank Osterfeld Sep 02 '12 at 20:10
  • @Frank Osterfeld per Tom Seddon advice it is not a bug just how it manages compile process order. If it fully compiles ( which I don't know if it will, still going ) then maybe a bug if one process is intended to start before another. – Brandon Clark Sep 02 '12 at 20:31

1 Answers1

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-j with no argument lets make decide. From your link, from the section for ‘-j [jobs]’:

With no argument, make runs as many recipes simultaneously as possible.

If the makefile is correctly written there should be no difference between running it with or without -j, though (as you note) running one job at a time could be slower.

Tom Seddon
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  • I guess that could be important. I am thinking it could because I am thinking of this example; I am supposed to compile a new configure.exe before I compile Qt. There may be similar process needed for the final Qt compile being controlled by the `-j` command. What do you think? – Brandon Clark Sep 02 '12 at 19:24
  • You compile configure.exe? You most probably just run it. – Frank Osterfeld Sep 02 '12 at 20:11
  • @Frank Osterfeld Special process for Qt Blackberry setup. – Brandon Clark Sep 02 '12 at 20:25