Not sure if this is the correct place to report this, but here goes anyway....
If you are running Mageia 2 using lilo as the boot loader, and install "mageia-prepare-upgrade", then 1) The process incorrectly includes the "vga=xxx" line into the append line, causing an error when lilo is run. 2) The process doesn't run lilo once the lilo.conf file has been modified, so the extra "Mageia 3 Prepare Upgrade" option never appears!
I know lilo is considered a slittle passe these days, but I still much prefer it to grub! At least you can get rid of lilo easily - grub seems almost impossible to remove...!
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Pete