I made a map in QGIS.

Now I want to export the resulting image (layers upon layers) for further processing in GDAL.

The print composer only lets me export an image up to a fixed size. If I try to make it bigger via resolution or paper size, it says there might be a memory leak and refuses to export.

How can I export my map at a very high resolution (think 100k pixels per side)? I know it sounds silly but I really want to do this.